ChatGPT answers, unedited

If your main requirement is consistent retargeting when someone moves from desktop to mobile, I’d shortlist these:

• Criteo — Strong fit for ecommerce. Its cross-device capability can use hashed email to recognize the same visitor across devices, and its dynamic retargeting can personalize ads based on products and shopper behavior. It reaches desktop, mobile web, apps, social, and other inventory. Criteo Help Center Criteo

criteo.com

• AdRoll — A good option if you want something more self-service. AdRoll supports cross-device targeting and can use hashed email addresses for matching; its campaigns cover desktop, mobile, apps, and other channels. AdRoll Help Center AdRoll Help Center

adroll.com

What I'd look for

The important capability isn't simply "retargeting." You want identity resolution + first-party data + frequency controls:

1. Visitor browses product on laptop.
2. They provide an email/login, or otherwise become matchable.
3. Platform associates that identity with their mobile device.
4. Mobile ad can reflect the product/category they viewed.
5. Once they purchase, they're automatically excluded from the retargeting audience.

That first-party identity layer matters because relying purely on third-party cookies is increasingly unreliable. AdRoll and Criteo both explicitly support hashed-email approaches for cross-device matching. AdRoll Help Center Criteo Help Center

If you're a DTC/ecommerce brand: I'd investigate Criteo and AdRoll first. If you tell me your approximate monthly ad spend, ecommerce platform (Shopify, WooCommerce, custom, etc.), and whether you need Meta/Instagram + Google + display all coordinated, I can narrow the options down and compare pricing/integration requirements.

If your goal is “someone visits on desktop, then sees relevant retargeting ads on their phone (and vice versa)”, the key capability is cross-device identity resolution, not merely ordinary retargeting.

Shortlist

My practical take

For maximum control and sophisticated cross-device programmatic, I'd investigate Google Display & Video 360 first. Google explicitly supports first-party audience targeting and connects audiences with Google's cross-device signals. Google Help Google Help

It also lets you target desktop, smartphone, tablet, and connected-TV inventory, while managing audiences across different environments. Google Help Google Help

For e-commerce, I'd put Criteo near the top of the evaluation list, particularly if product-level dynamic retargeting is important.

For simpler implementation, Google Ads and Meta can accomplish a lot without adopting a full DSP, although you're more dependent on their respective ecosystems.

One important distinction

Don't confuse:

• Same-device retargeting: visitor sees your ad again on the same browser/device.
• Cross-device retargeting: desktop visitor can subsequently be recognized on their phone/tablet.
• Cross-platform retargeting: the system can reach them across different publishers, apps, websites, and potentially CTV.

For your stated requirement, you specifically want the second and ideally third.

Also, no platform can guarantee perfect person-level matching. Browser restrictions, consent, unavailable cookies/device IDs, and platform privacy controls mean cross-device matching is probabilistic or dependent on authenticated/first-party signals in many environments. Google's own documentation notes fluctuations when cookies and device IDs aren't available. Google Help

If you tell me your monthly ad spend, B2B vs. e-commerce, and whether you need display/video only or also social, I can narrow this to 2–3 platforms and compare pricing, identity matching, setup difficulty, dynamic creative, frequency capping, and attribution.

For e-commerce, I'd put Criteo near the top of the evaluation list, particularly if product-level dynamic retargeting is important.

For simpler implementation, Google Ads and Meta can accomplish a lot without adopting a full DSP, although you're more dependent on their respective ecosystems.

One important distinction

Don't confuse:

• Same-device retargeting: visitor sees your ad again on the same browser/device.
• Cross-device retargeting: desktop visitor can subsequently be recognized on their phone/tablet.
• Cross-platform retargeting: the system can reach them across different publishers, apps, websites, and potentially CTV.

For your stated requirement, you specifically want the second and ideally third.

Also, no platform can guarantee perfect person-level matching. Browser restrictions, consent, unavailable cookies/device IDs, and platform privacy controls mean cross-device matching is probabilistic or dependent on authenticated/first-party signals in many environments. Google's own documentation notes fluctuations when cookies and device IDs aren't available.

Best fits:

• criteo.com — strongest fit for ecommerce/product retargeting; supports personalized ads across desktop, mobile, apps, and open-web inventory using cross-device identity. Criteo Criteo Help Center
• marketingplatform.google.com — better for sophisticated programmatic teams; Google explicitly supports cross-device dynamic remarketing and cross-device conversion measurement. Google Help Google Help
• thetradedesk.com — strong enterprise omnichannel option with a cross-device identity framework and measurement across devices/channels. The Trade Desk The Trade Desk

Quick pick: Criteo for ecommerce; DV360 for maximum Google ecosystem control; The Trade Desk for broader omnichannel programmatic.

For consistent retargeting across desktop and mobile, the best software depends on your scale, channels, and how much identity matching you need. The strongest options today are usually a mix of ad platforms (Google/Meta), DSPs, and customer data platforms (CDPs) rather than a single magic tool. Cross-device targeting typically relies on logged-in user signals, first-party data, or identity graphs to connect a person’s activity across devices. Experience League choozle

Best cross-device retargeting platforms

My shortlist by use case

Ecommerce store

1. Criteo — best for dynamic product retargeting.
2. ads.google.com + facebook.com — usually the highest-impact baseline.
3. AdRoll — easier if you want a simpler all-in-one retargeting workflow.

SaaS / lead generation

1. business.linkedin.com + Google Ads — good for account and intent targeting.
2. business.adobe.com or another CDP — useful when you need CRM-based audiences.
3. The Trade Desk — for larger budgets and programmatic reach.

Enterprise with many channels

• The Trade Desk
• business.adobe.com
• marketingplatform.google.com

Features I would prioritize

Look for:

• People-based identity matching (not just browser cookies)
• Frequency capping across devices (avoid showing the same ad 20 times on phone + laptop)
• Dynamic creative optimization (different products/messages by behavior)
• CRM/CDP audience syncing
• Cross-device attribution reporting
• Server-side tracking options as browser privacy changes continue

Experience LeagueA practical stack for many companies is:

• Google Ads + Meta Ads for core retargeting
• A CDP/CRM audience layer for known customers and leads
• AdRoll/Criteo/DSP only if you need broader display inventory or more automation

If you share your business type (ecommerce, SaaS, app, publisher), monthly ad spend, and channels (Google, Meta, TikTok, LinkedIn, etc.), I can narrow this to a few best-fit options.

If your goal is specifically “someone browses on desktop, then sees relevant ads on their phone—and vice versa,” I’d shortlist these:

My pick: AdRoll

AdRoll is probably the best starting point if you want one platform to coordinate retargeting across desktop web, mobile web/apps, social, video and potentially CTV. Its cross-device identity capabilities are specifically designed to connect users across browsers and devices, and its campaigns can use website/app visitors and CRM audiences. AdRoll AdRoll

adroll.com

It also supports dynamic retargeting, so someone who viewed Product A can subsequently see Product A—or relevant recommendations—rather than just receiving a generic brand ad. AdRoll

If you're a serious ecommerce operation: Criteo

Criteo is the stronger choice when product-level personalization and scale matter more than simplicity. Its system uses commerce-intent signals to dynamically select products, bids and timing, and it explicitly supports experiences across desktop, mobile, tablet and apps. Criteo Criteo Help Center

criteo.com

One important caveat

“Cross-device retargeting” doesn't mean every anonymous desktop visitor can always be deterministically identified on their phone. Modern privacy restrictions, consent requirements, browser limitations and walled gardens make identity resolution the critical capability. Platforms that can combine first-party identifiers (login/email/CRM), consented data and their own identity graphs generally perform better than simply dropping a retargeting pixel.

My ranking for your stated use case:

1. AdRoll — best balance of cross-device + ease + multichannel.
2. Criteo — best for sophisticated ecommerce/product retargeting.
3. DV360 — best if you have an enterprise programmatic team.
4. Meta — excellent complement for reaching users inside Facebook/Instagram, but I wouldn't use it as the only cross-device retargeting system.

If you tell me your monthly ad spend, ecommerce vs. SaaS, and whether visitors typically log in, I can narrow this to the best 1–2 options and explain exactly how I'd set up the cross-device audience flow.

AdRoll is probably the best starting point if you want one platform to coordinate retargeting across desktop web, mobile web/apps, social, video and potentially CTV. Its cross-device identity capabilities are specifically designed to connect users across browsers and devices, and its campaigns can use website/app visitors and CRM audiences. AdRoll AdRoll

adroll.com

It also supports dynamic retargeting, so someone who viewed Product A can subsequently see Product A—or relevant recommendations—rather than just receiving a generic brand ad. AdRoll

If you're a serious ecommerce operation: Criteo

Criteo is the stronger choice when product-level personalization and scale matter more than simplicity. Its system uses commerce-intent signals to dynamically select products, bids and timing, and it explicitly supports experiences across desktop, mobile, tablet and apps. criteo.com help.criteo.com

If your main goal is “someone browses on their phone, then later sees relevant ads on their laptop—and vice versa,” I’d shortlist these:

🥇 My pick: Criteo

For a retailer or e-commerce business, Criteo is probably the most direct fit. Its current Dynamic Retargeting product uses commerce signals to personalize products/creative and reaches users across open web, social, video and in-app inventory. Its Shopper Graph is specifically designed to connect activity across devices. Criteo Criteo

criteo.com

🏢 Best enterprise option: Adobe + LiveRamp

If you have a substantial CRM/first-party identity database, Adobe Advertising DSP with LiveRamp's device graph is particularly compelling. It can extend known audiences across a person's devices and apply frequency caps at the person, rather than individual-device, level. Experience League

That's useful for avoiding the classic problem where someone sees the same retargeting ad 10 times on their phone and another 10 times on their laptop.

What I'd choose by situation

• E-commerce, DTC, retail: Criteo
• Large enterprise with CRM/identity infrastructure: Adobe + LiveRamp
• Performance-focused programmatic retargeting: RTB House
• Already heavily invested in Google: Google Ads
• Your customers spend significant time on Instagram/Facebook: Meta Ads

One important distinction: cross-device retargeting isn't simply “tracking the same cookie on two devices.” The stronger platforms use identity/device graphs or authenticated/declared identifiers to determine that multiple devices belong to the same person. Adobe, for example, explicitly supports people-based targeting and frequency management across known devices. Experience League Experience League

If you tell me your business type, monthly ad spend, and whether visitors log in/create accounts, I can narrow this to the best 2–3 platforms and compare expected setup complexity, pricing model, identity matching, and mobile/desktop coverage.

🏢 Best enterprise option: Adobe + LiveRamp

If your goal is “someone browses on mobile, then sees a relevant ad later on desktop—and vice versa,” I’d shortlist these:

My recommendation

For most e-commerce businesses: start with Criteo. Its Shopper Graph is specifically designed to connect shopper activity across devices, and its dynamic retargeting can personalize ads based on products and purchase intent. Criteo also documents using hashed emails to connect mobile and desktop activity. Criteo Criteo Criteo Help Center

For a larger organization with CRM, website, app, offline data, and multiple advertising channels, I'd choose Adobe Real-Time CDP + Adobe Advertising. Adobe can build unified profiles across known and anonymous data and activate audiences across channels and devices; its current Advertising DSP integration supports hashed email, universal IDs, and mobile advertising IDs. Experience League Experience League

One important caveat: “cross-device” isn't simply a matter of dropping the same cookie on every device. You want an identity solution that can legitimately recognize the same person across devices, ideally using authenticated/first-party signals plus privacy-compliant identity resolution. Adobe's documentation, for example, explicitly describes moving from device-level targeting toward people-based targeting with device graphs. Experience League

If you tell me your business type, monthly website traffic/ad spend, and whether you sell products or services, I can narrow this to the 2–3 best platforms and compare pricing, setup difficulty, Facebook/Google integration, and cross-device matching.

For consistent retargeting across desktop and mobile, the best software depends on whether you want a simple campaign tool, ecommerce personalization, or enterprise-level identity resolution. Cross-device retargeting works by connecting a person’s activity across screens (often using logged-in audiences, CRM matching, device graphs, or consent-based identity signals), then serving coordinated ads rather than treating each device as a separate visitor. Shopify

Best cross-device retargeting platforms

My shortlist by scenario

If you are an ecommerce brand

1. Criteo — best for product-feed retargeting (“show the exact items someone viewed”). PPC Marketing Hub
2. Meta + Google Ads together — often the highest-ROI combination for smaller and mid-sized stores.
3. AdRoll — good if you want one simpler dashboard across display/social/email. BestPage

If you are B2B / SaaS

1. Google Ads Customer Match + LinkedIn Ads + CRM syncing
2. The Trade Desk for larger budgets and account-based campaigns. Guideflow
3. A customer data platform (CDP) or identity resolution layer if your buying cycle spans many devices and people.

If you want the easiest setup

• Start with Google Ads remarketing + Meta retargeting.
• Add AdRoll if you need coordinated display/email/social campaigns without building a larger ad-tech stack. BestPage

Features I would prioritize

• First-party audience matching (email/CRM/customer lists)
• Cross-device attribution reporting
• Frequency caps (avoid showing the same ad endlessly)
• Dynamic creative (change ads based on viewed products/pages)
• Server-side tracking support (browser privacy changes have made pixel-only tracking less reliable) Opensend
• Consent/privacy controls for your regions and audience types

For most companies, the practical winning stack is:

• Google Ads + Meta Ads for reach
• CRM/CDP integration for known users
• Criteo or AdRoll if you need more advanced personalization or automation

If you share your business type (ecommerce, SaaS, lead gen, publisher), monthly ad spend, and channels you already use, I can narrow this to 2–3 best-fit options.

If your main requirement is “someone browses on desktop, then sees relevant retargeting ads on their phone—and ideally gets consistent frequency/personalization across both,” I’d shortlist these:

1. The Trade Desk — best if cross-device consistency is the priority

The Trade Desk's Identity Alliance/cross-device graph is specifically designed to connect people across devices and channels, allowing advertisers to manage targeting and frequency across the customer journey. It supports first-party data plus identifiers such as UID2. The Trade Desk The Trade Desk

That makes it particularly attractive if you want:

• Desktop → mobile → tablet → CTV continuity
• Cross-device frequency capping
• First-party CRM audiences
• Programmatic display/video/CTV
• More sophisticated audience and measurement controls

I'd choose this for a larger marketing team or meaningful ad spend.

2. Criteo — best for ecommerce

Criteo is especially compelling if “relevant ads” means showing the products a visitor viewed or products they're likely to buy next. Its Shopper Graph connects shopping behavior across devices, while Dynamic Retargeting automatically personalizes product ads. Criteo Criteo

It's a particularly good fit for:

• Ecommerce
• Large product catalogs
• Dynamic product ads
• Abandoned-browse/cart retargeting
• Desktop + mobile web + app audiences

3. RTB House — strong performance-focused option

RTB House is worth evaluating if your priority is conversion performance rather than building a broader omnichannel media stack. It competes directly in the retargeting/DSP space with Criteo and The Trade Desk. RTB House

4. AdRoll — easiest for smaller teams

AdRoll is simpler if you don't have a dedicated programmatic media team. It supports cross-platform retargeting and has historically positioned cross-device targeting around connecting browser behavior across devices. AdRoll AdRoll

What I'd pick

Ecommerce: Criteo
Enterprise / sophisticated omnichannel: The Trade Desk
Performance-focused retargeting: RTB House
Small/mid-size company wanting simplicity: AdRoll

One important caveat: cross-device doesn't mean every anonymous desktop visitor can be perfectly recognized on their phone. Modern solutions increasingly rely on first-party/authenticated identifiers and identity graphs rather than simply matching third-party cookies. The Trade Desk, for example, explicitly combines multiple identity types and cross-device graphs for this reason. The Trade Desk The Trade Desk

If you tell me your monthly ad spend, B2B vs. ecommerce, website/app setup, and whether you're already using Google/Meta, I can narrow this to the best 2–3 options and compare pricing, implementation difficulty, identity matching, and attribution.

If your goal is specifically “someone visits on desktop, then sees relevant ads on their phone/tablet later”, I’d shortlist these:

1. Criteo — best overall for most e-commerce

criteo.com

Criteo's Shopper Graph explicitly connects identifiers across users' screens, while its retargeting product dynamically recommends products based on shopper behavior. It supports desktop, mobile web and apps, making it particularly well suited to the scenario you're describing. Criteo Criteo Criteo Help Center

Pick Criteo if: you sell products online and want relatively turnkey “viewed product → personalized ad → conversion” campaigns.

2. The Trade Desk — best for sophisticated cross-device identity

thetradedesk.com

The Trade Desk is stronger when you want to build a broader omnichannel media strategy rather than just traditional retargeting. Its identity stack includes a cross-device graph and Unified ID 2.0, with cross-device frequency management and measurement across channels. The Trade Desk The Trade Desk The Trade Desk

Pick TTD if: you're spending enough to justify a DSP and want desktop + mobile + CTV + other programmatic inventory managed together.

3. RTB House — strong performance/retargeting alternative

rtbhouse.com

RTB House specializes heavily in personalized performance advertising and next-generation retargeting, including dynamic product recommendations and first-party signals across web and app environments. RTB House RTB House

Pick RTB House if: your primary KPI is ROAS/conversions, particularly for an e-commerce catalog.

One important caveat

No platform can literally guarantee that an anonymous desktop visitor is the same individual using a particular phone. Modern cross-device targeting relies on combinations of first-party identifiers, consented login/email signals, device/identity graphs, and probabilistic signals. The Trade Desk, for example, increasingly emphasizes cross-identifier rather than simply device-based targeting. The Trade Desk

My ranking:
Criteo → easiest/best for e-commerce retargeting
The Trade Desk → best enterprise/omnichannel infrastructure
RTB House → excellent performance-focused alternative

If you tell me your business type, monthly ad spend, and whether you need web-only or web + app + CTV, I can narrow this to the best 1–2 options and compare pricing/integration requirements.

For cross-device retargeting (so someone who visits on mobile can later see consistent, relevant ads on desktop—and vice versa), the best software depends on your scale, ad channels, and whether you need identity resolution or just campaign management. The key capability is an identity graph that links devices/users while respecting consent and privacy rules. Experian ID5

Best options by use case

WifiTalents Guideflow## My shortlist

For ecommerce brands

• Criteo — good when you want dynamic product ads (“show the shoes they viewed”) across devices.
• Google Ads + GA4 audiences + Enhanced Conversions — often the simplest stack if you already have Google traffic.
• AdRoll — practical if you need something your marketing team can launch quickly.

For enterprise marketing teams

• The Trade Desk + an identity partner (LiveRamp, Tapad, ID5, etc.) — better when you need display, mobile, CTV, frequency control, and unified measurement. Guideflow ID5

For a first-party data strategy

• LiveRamp, Tapad, Experian, or ID5 — these are more identity-layer tools than “ad managers”; they help resolve users across browsers, apps, and devices so downstream platforms can target more consistently. Experian ID5

Features I would prioritize

1. Deterministic matching (logged-in users, CRM identifiers, consented data) rather than relying only on probabilistic matching.
2. Frequency capping across devices so someone does not see the same ad 20 times on phone + laptop.
3. Sequential messaging (e.g., mobile visitor sees awareness ad → desktop visitor sees offer ad).
4. Server-side conversion tracking to improve signal quality as browser tracking becomes more restricted.
5. Consent and privacy controls built into identity handling. Ketch

If you tell me your setup (ecommerce vs SaaS, monthly ad spend, channels like Google/Meta/CTV, and whether you have a CRM/email list), I can narrow this to 2–3 best-fit choices.

If your main goal is “a visitor browses on desktop, then sees relevant ads on their phone later—and vice versa,” I’d shortlist these:

My recommendation

For a serious cross-device program, I'd start with The Trade Desk. Its identity stack combines first-party data with UID2 and a cross-device graph, explicitly designed to provide a unified customer view across channels and devices. The Trade Desk The Trade Desk Partner Portal

For e-commerce, I'd probably choose Criteo instead. Its Shopper Graph is specifically designed to connect shopper behavior and product/category signals and identify shoppers across devices. Criteo also supports web and app retargeting across desktop, mobile web, and in-app environments. Criteo Criteo Help Center

RTB House is particularly interesting if you're optimizing aggressively for purchases rather than simply maximizing reach. Its current offering combines personalized retargeting, first-party signals, and deep-learning optimization across web and app. RTB House RTB House

One important distinction

Don't buy a platform solely because it says “cross-device.” There are two very different approaches:

• Deterministic: the platform can associate devices using authenticated/consented identifiers such as email-based IDs. Generally the more reliable approach.
• Probabilistic: the platform infers that multiple devices belong to the same person/household from behavioral and technical signals. Broader, but less certain.

For example, The Trade Desk's UID2 turns consented first-party email/phone information into pseudonymous identifiers designed for cross-device and omnichannel activation. The Trade Desk Partner Portal Unified ID

If you tell me your business type (e-commerce, SaaS, B2B, travel, etc.), monthly ad spend, and whether you need web-only or web + app + CTV, I can narrow this to the best 2–3 platforms and compare pricing, identity matching, integrations, and setup complexity.

If your goal is “a visitor sees a relevant retargeting ad on their phone, then later on their laptop (or vice versa), without treating them as two different people,” you’re looking for a platform with identity resolution / cross-device graphing, not just a basic retargeting pixel. Cross-device systems typically work by linking privacy-safe identifiers across browsers, mobile devices, apps, and other channels so campaigns can manage reach and frequency at the person level. G2 ID5

Here are strong options by use case:

My shortlist by company size

Small ecommerce / DTC brand

Start with:

• adroll.com
• criteo.com
• Native integrations from facebook.com and ads.google.com

These are usually faster to deploy than building an identity layer.

Growing brand with meaningful first-party data

Consider:

• segment.com + ad platform integrations
• hightouch.com
• salesforce.com

The advantage is that you control the customer identity data instead of relying only on third-party audiences.

Enterprise / global advertising

Look at:

• liveramp.com
• thetradedesk.com
• tapad.com
• id5.io

These are better suited for large budgets, multiple channels, and stricter measurement requirements. WifiTalents ID5

Features I’d require before buying

• Deterministic matching (login, email, CRM IDs) where possible
• Probabilistic matching for anonymous visitors
• Frequency capping across devices (avoid showing the same person 20 ads)
• Server-side event tracking to improve signal quality
• Consent/privacy controls (GDPR, CCPA, etc.)
• Audience sync to Meta, Google, TikTok, DSPs, and CTV
• Incrementality testing so you know retargeting is actually driving sales

One important distinction: if you only need “same website visitor gets ads on Facebook/Google after leaving,” a standard retargeting platform is enough. If you need “mobile visitor today = desktop visitor next week = same person,” you need an identity-resolution layer. G2 ID5

If you share your stack (Shopify/WooCommerce/custom site, ad channels, monthly spend, B2B vs B2C), I can narrow this to 2–3 best-fit choices.

If your goal is “someone browses on desktop, then sees the same/relevant product ads on their phone later”, I’d shortlist these:

1. adroll.com — best overall for SMB/mid-market

• Explicit cross-device tracking for phone, tablet, and desktop.
• Runs display, native, mobile, video, social, and CTV from one platform.
• Supports dynamic product retargeting based on what the visitor viewed.
• Relatively straightforward compared with enterprise DSPs. AdRoll AdRoll Help Center AdRoll
• criteo.com — best for ecommerce at scale

• Particularly strong if you have a large product catalog.
• Its dynamic retargeting uses commerce signals to personalize product recommendations rather than simply showing the last item viewed.
• Supports web, social, mobile and app environments. Criteo Help Center Criteo
• rtbhouse.com — best performance-focused alternative

• Strong emphasis on personalized product recommendations and deep-learning optimization.
• Particularly interesting for ecommerce brands spending enough on programmatic advertising to benefit from sophisticated optimization. RTB House RTB House

My pick

For most businesses: AdRoll. It is the most direct match for your requirement because cross-device tracking is an explicit feature, and it combines web/mobile/social/CTV retargeting rather than forcing you to manage separate campaigns. AdRoll Help Center AdRoll

For a sizable ecommerce operation: Criteo would be my first evaluation, especially if personalized product recommendations and ROAS are more important than simplicity.

One important caveat: cross-device doesn't necessarily mean perfect person-level identification. AdRoll's cross-device functionality, for example, involves hashed email data and requires appropriate disclosure/permission when that data is collected and hashed. AdRoll Help Center

If you tell me your website platform (Shopify, WordPress, custom, etc.), monthly visitors/ad budget, and whether you need Facebook/Instagram included, I can narrow this to the best 2–3 options and compare pricing, setup difficulty, and cross-device capabilities.

If your priority is “someone browses on desktop, then sees relevant ads on their phone—and vice versa,” I’d shortlist these:

My top picks

1. Criteo — best for true retargeting

Criteo is particularly strong if you're an e-commerce company. Its Shopper Graph is designed to connect activity across devices, and its retargeting can deliver personalized ads across desktop, mobile, tablet, apps and the open web. Criteo Criteo Help Center

Its dynamic creative system can also change the products/content shown based on shopper behavior, rather than simply showing everyone the same banner. Criteo Criteo

criteo.com

2. Google Ads — best if you want scale

Google is particularly compelling because cross-device behavior is built into its conversion measurement. Google can connect observed and modeled conversions when someone interacts on one device and converts on another. Google Help Google Help

Its remarketing can reach previous website visitors across the Display Network, apps, YouTube and other Google inventory, including cross-device situations. Google Help

ads.google.com

3. Meta Platforms — best for social retargeting

If your customers spend substantial time on Instagram/Facebook, Meta is an important complementary channel. I'd generally use it alongside Google/Criteo, rather than expecting it to cover the entire open web.

What I'd choose

• E-commerce + personalized product ads: Criteo
• B2B/SaaS or general website: Google Ads + Meta
• Large enterprise with a dedicated media team: The Trade Desk + Google/Meta
• Small team wanting easy setup: AdRoll
• Need the most consistent experience across web + app + devices: Criteo, assuming its inventory and identity capabilities fit your market.

One important distinction: “cross-device retargeting” doesn't mean you can deterministically identify every visitor on every device. Privacy restrictions, consent, browser limitations and users not being logged in mean platforms increasingly rely on first-party identifiers, platform login data and/or modeled attribution. Google explicitly uses modeling for some cross-device conversions, for example. Google Help

If you tell me your business type (e-commerce, SaaS, lead gen, etc.), monthly ad spend, and whether you have a mobile app, I can narrow this to the best 2–3 platforms and explain exactly how I'd set up the cross-device retargeting stack.

Its dynamic creative system can also change the products/content shown based on shopper behavior, rather than simply showing everyone the same banner. Criteo Criteo

criteo.com

2. Google Ads — best if you want scale

Google is particularly compelling because cross-device behavior is built into its conversion measurement. Google can connect observed and modeled conversions when someone interacts on one device and converts on another. support.google.com support.google.com

Its remarketing can reach previous website visitors across the Display Network, apps, YouTube and other Google inventory, including cross-device situations. support.google.com

ads.google.com

3. Meta Platforms — best for social retargeting

If your goal is specifically “someone visits on mobile, then sees relevant retargeting ads on desktop (and vice versa)”, I’d shortlist these:

My recommendation

For an e-commerce company: start with Criteo + Meta + Google rather than looking for one magical retargeting platform.

Criteo is particularly relevant because its Shopper Graph is designed to connect behavior across devices and its network spans web, mobile browsers and apps. Criteo Criteo

For a broader B2B/SaaS advertiser: I'd lean toward Google Ads/Display & Video 360 + Meta, with your CRM/CDP supplying first-party audiences. Google explicitly supports remarketing across websites/apps and reports modeled cross-device conversions. Google Help Google Help

One important distinction

“Cross-device retargeting” can mean two different things:

1. Same person, different device — mobile visit → desktop ad.
2. Consistent creative/product relevance — the user sees the product/content they actually viewed, regardless of device.

You want a platform that does both, ideally using first-party identifiers where consent allows. Google, for example, uses privacy-safe observed/modelled signals for cross-device measurement rather than claiming every cross-device journey is directly observed. Google Help Google Help

If you tell me your business type (e-commerce, SaaS, lead gen, etc.), monthly ad spend, and whether you need web + mobile app, I can narrow this to the top 2–3 platforms and compare pricing, audience matching, identity resolution, and setup complexity.

For a broader B2B/SaaS advertiser: I'd lean toward Google Ads/Display & Video 360 + Meta, with your CRM/CDP supplying first-party audiences. Google explicitly supports remarketing across websites/apps and reports modeled cross-device conversions.

If your main goal is “someone browses on their phone, then sees relevant ads on their laptop later”, I’d shortlist these:

1. criteo.com — best overall for cross-device retargeting

• Strong identity graph designed to connect shoppers across screens. Criteo
• Can use hashed email/customer IDs to improve cross-device matching—for example, mobile browsing → desktop retargeting. Criteo Help Center Criteo Docs
• Particularly strong for ecommerce because its dynamic ads can automatically personalize products, pricing, availability, and recommendations. Criteo
• Supports web, in-app, video, social, desktop, mobile, and tablet environments. Criteo Help Center Criteo Help
• My pick if cross-device consistency is the primary requirement.
• ads.google.com — best if you want broad reach and simpler implementation

• Google supports remarketing across websites/apps and can reach previous mobile-site visitors across devices. Google Help
• Dynamic remarketing can show the specific products/services someone previously viewed. Google Help
• Great fit if you're already using Google Analytics, Merchant Center, YouTube, or Performance Max.
• Best value for many SMBs, although you have less control over the identity-resolution layer than with a dedicated retargeting platform.
• rtbhouse.com — best performance-oriented alternative to Criteo

• Strong programmatic retargeting and deep-learning optimization.
• Often used alongside Google and Meta rather than as the only retargeting channel. RTB House
• Worth testing if you're spending enough for incremental performance testing.
• facebook.com — best for social retargeting

• Particularly useful if your audience spends significant time on Instagram/Facebook.
• I'd generally use it alongside, rather than instead of, a cross-device web-retargeting platform.

What I'd choose

One important caveat: no platform can magically identify every anonymous mobile visitor as the same person on desktop. The strongest setup uses first-party identity signals—especially a stable customer ID for logged-in users and properly consented hashed email—alongside the platform's own identity graph. Criteo, for example, explicitly recommends customer IDs and hashed emails for improving cross-device matching. Criteo Help Center help.cyield.criteo.com

If you tell me your monthly ad spend, ecommerce vs. lead-gen, traffic volume, and whether users log in, I can narrow this down to the 2–3 platforms I'd actually test and how I'd structure the cross-device setup.

If your goal is specifically “someone visits on mobile, then sees relevant retargeting on their laptop/desktop (and vice versa)”, I’d shortlist these:

My picks

1. Best overall: Google DV360

If you're spending enough to justify a DSP, this would be my first choice. DV360 supports first-party audience lists, device targeting across desktop, smartphone, tablet and CTV, and Google cross-device signals. Google Help Google Help

It also lets you manage web/app inventory and frequency more systematically. Google explicitly supports cross-environment conversion reporting and frequency controls for relevant audience setups. Google Help

marketingplatform.google.com

2. Best for e-commerce: Criteo

If you're selling products and want the platform to automatically determine which products/messages to show a visitor, Criteo is particularly worth evaluating. It's more specialized around commerce retargeting than a general-purpose DSP.

3. Best performance alternative: RTB House

I'd put RTB House alongside Criteo if your primary KPI is ROAS/conversions rather than brand reach. It's particularly relevant when you have a substantial amount of product/catalog and conversion data.

4. Easiest route: Meta Ads

If your audience is active on Instagram/Facebook, Meta can give you a relatively straightforward retargeting setup. It's especially attractive when you can identify users through your own first-party/customer data rather than relying solely on anonymous browser tracking.

One important distinction

“Cross-device retargeting” can mean two different things:

• Same-device: visitor browses on their phone → sees an ad later on that same phone.
• True cross-device: visitor browses on their phone → is recognized as the same person when they later use a laptop → receives the retargeting ad there.

The second is substantially harder because cookies/device IDs aren't universally available. Google itself notes that delivery can fluctuate when cookies or device IDs aren't available. Google Help

So if true person-level cross-device continuity is the requirement, I'd prioritize a platform with strong identity resolution + first-party data integrations, rather than simply choosing a platform that advertises itself as “cross-device.”

My practical ranking:
DV360 → best overall/control
Criteo → best e-commerce
RTB House → best performance/e-commerce alternative
Meta → best simplicity/social reach
StackAdapt → best B2B/programmatic alternative

If you tell me your monthly ad spend, B2B vs. B2C, and whether you sell online, I can narrow this to the 2–3 platforms I'd actually test.

2. Best for e-commerce: Criteo

If you're selling products and want the platform to automatically determine which products/messages to show a visitor, Criteo is particularly worth evaluating. It's more specialized around commerce retargeting than a general-purpose DSP.

3. Best performance alternative: RTB House

I'd put RTB House alongside Criteo if your primary KPI is ROAS/conversions rather than brand reach. It's particularly relevant when you have a substantial amount of product/catalog and conversion data.

4. Easiest route: Meta Ads

If your audience is active on Instagram/Facebook, Meta can give you a relatively straightforward retargeting setup. It's especially attractive when you can identify users through your own first-party/customer data rather than relying solely on anonymous browser tracking.

One important distinction

“Cross-device retargeting” can mean two different things:

• Same-device: visitor browses on their phone → sees an ad later on that same phone.
• True cross-device: visitor browses on their phone → is recognized as the same person when they later use a laptop → receives the retargeting ad there.

The second is substantially harder because cookies/device IDs aren't universally available. Google itself notes that delivery can fluctuate when cookies or device IDs aren't available.

So if true person-level cross-device continuity is the requirement, I'd prioritize a platform with strong identity resolution + first-party data integrations, rather than simply choosing a platform that advertises itself as “cross-device.”

If your goal is specifically “someone visits on desktop, then sees relevant retargeting ads on their phone—and vice versa,” I’d shortlist these:

1. criteo.com — best for e-commerce/product retargeting.

Strong dynamic retargeting, personalized product recommendations, and reach across web, mobile, apps, and social. Criteo uses identity matching to connect users across devices. Criteo Criteo

2. business.adobe.com — best for sophisticated enterprise cross-device campaigns.

It supports people-based targeting across known devices, including frequency capping across devices, with LiveRamp's device graph integration. Experience League

3. thetradedesk.com — best for broad programmatic/omnichannel buying.

Particularly good if you want desktop + mobile + CTV + audio rather than just website retargeting. Adobe's current integration supports audience activation into The Trade Desk, and TTD has demonstrated cross-device retargeting campaigns. Experience League The Trade Desk

4. rtbhouse.com — strong alternative for performance-focused e-commerce.

Its pitch is deep-learning-powered retargeting across web and app, with personalized product recommendations and first-party data activation. RTB House

My pick

The important distinction is that cross-device retargeting isn't simply putting the same pixel on desktop and mobile. You want an identity graph that can recognize that the laptop and phone belong to the same person, ideally using first-party/authenticated identifiers. Adobe, for example, can stitch a CRM ID, hashed email, loyalty ID, etc. to device-level activity. Experience League

Also look for cross-device frequency capping and conversion suppression. Otherwise someone who bought on their laptop could keep seeing the same acquisition ad on their phone. Adobe explicitly supports cross-device suppression and frequency management. Experience League

If you tell me your business type, monthly ad spend, and whether you're using Shopify/GA4/HubSpot/Salesforce, I can narrow this to the 2–3 best options and compare pricing, setup difficulty, identity matching, and Facebook/Google integration.

For cross-device retargeting (a visitor sees an ad on mobile, later on desktop, and the experience stays consistent), the best software depends on your scale, ad channels, and whether you want platform-native retargeting or a dedicated identity resolution layer. Cross-device targeting increasingly relies on identity graphs and first-party signals because browser cookies are less reliable. Opensend LeadJourney

Best options by use case

My shortlist

For a small or mid-size ecommerce brand

1. Meta Ads + Google Ads remarketing + server-side tracking

• Lowest complexity.
• Use customer lists, purchase events, and conversion APIs where possible.
• Klaviyo + Meta/Google integrations

• Best if you already have email/SMS subscribers.
• A dedicated identity tool (if anonymous traffic is large)

• Useful when you need to recognize visitors who browse on one device and return on another. Opensend

For a large brand spending heavily on ads

• Twilio Segment or LiveRamp for customer identity infrastructure.
• Tapad for media buying and cross-device reach measurement. WifiTalents LeadJourney

Features to prioritize

Look for:

• Deterministic matching (login, email, phone, CRM IDs)
• Probabilistic/device graph matching as a supplement
• Server-side event tracking
• Frequency capping across devices
• Audience syncing to Google, Meta, TikTok, CTV, and DSPs
• Consent/privacy controls (GDPR/UK GDPR if you operate in the UK)

A typical modern stack looks like:

Website/app events → customer data platform or identity layer → audience builder → Google/Meta/TikTok/DSP campaigns

If you share your setup (Shopify/ecommerce vs B2B, monthly ad spend, and whether you mainly use Google, Meta, TikTok, or programmatic), I can narrow this to the best 2–3 choices.

If your main goal is “someone visits on desktop, then sees a relevant ad on their phone (and vice versa)”, I’d shortlist these:

My top pick: AdRoll

adroll.com is probably the best starting point if you want something relatively straightforward rather than building an enterprise ad stack.

Its current platform supports display, native, video, mobile, social, CTV and DOOH, and AdRoll says its identity graph contains 5.4 billion cross-device identifiers. It can therefore connect audiences across devices rather than treating the laptop and phone as entirely separate visitors. AdRoll AdRoll

It also has frequency capping and cross-channel attribution, which are important—you don't want someone who visited once on desktop to get hammered with the same ad on their phone. AdRoll AdRoll

Best for ecommerce: Criteo

criteo.com is the one I'd investigate if you have a substantial product catalog and want dynamic product retargeting.

Criteo's Shopper Graph is specifically designed to connect shopping behavior across devices, browsers and apps and use those signals to determine which products to show. Criteo

Best for sophisticated programmatic buying: StackAdapt

stackadapt.com makes more sense if you're running significant media spend and want broader omnichannel programmatic capabilities rather than simply “retarget my website visitors.” It supports coordinated campaigns across multiple channels, and Forrester recognized it as a Strong Performer in its 2026 omnichannel advertising evaluation. StackAdapt

One important caveat

No platform can magically know that an anonymous desktop browser and an anonymous phone belong to the same person with 100% certainty. The strongest setup combines first-party identifiers—logged-in users, hashed email/CRM data, etc.—with privacy-compliant identity graphs. Adobe, for example, integrates LiveRamp's people-based device graph to extend audiences across known devices and manage frequency across them. Experience League

My recommendation:

• <$10k/month ad spend: AdRoll
• Ecommerce with a sizable catalog: Criteo
• $10k–$100k+/month and sophisticated media buying: StackAdapt or Criteo
• Large enterprise + Adobe ecosystem: Adobe Advertising

If you tell me your monthly ad spend, B2B vs. B2C, and whether you need Meta/Google/CTV in addition to display, I can narrow this to the 2–3 platforms I'd actually demo.

adroll.com is probably the best starting point if you want something relatively straightforward rather than building an enterprise ad stack.

Its current platform supports display, native, video, mobile, social, CTV and DOOH, and AdRoll says its identity graph contains 5.4 billion cross-device identifiers. It can therefore connect audiences across devices rather than treating the laptop and phone as entirely separate visitors. AdRoll AdRoll

It also has frequency capping and cross-channel attribution, which are important—you don't want someone who visited once on desktop to get hammered with the same ad on their phone. AdRoll AdRoll

Best for ecommerce: Criteo

criteo.com is the one I'd investigate if you have a substantial product catalog and want dynamic product retargeting.

Criteo's Shopper Graph is specifically designed to connect shopping behavior across devices, browsers and apps and use those signals to determine which products to show. criteo.com

Best for sophisticated programmatic buying: StackAdapt

stackadapt.com makes more sense if you're running significant media spend and want broader omnichannel programmatic capabilities rather than simply “retarget my website visitors.” It supports coordinated campaigns across multiple channels, and Forrester recognized it as a Strong Performer in its 2026 omnichannel advertising evaluation.

One important caveat

No platform can magically know that an anonymous desktop browser and an anonymous phone belong to the same person with 100% certainty. The strongest setup combines first-party identifiers—logged-in users, hashed email/CRM data, etc.—with privacy-compliant identity graphs. Adobe, for example, integrates LiveRamp's people-based device graph to extend audiences across known devices and manage frequency across them.

For cross-device retargeting (someone visits on desktop, later sees a relevant ad on mobile, and frequency/campaign logic stays consistent), the best software depends on your scale, channels, and data maturity. The strongest options are:

My typical recommendations by use case

• Shopify / ecommerce store:

Start with Criteo + Meta Platforms + Google Ads remarketing. Product-feed-based ads usually outperform generic banners because the creative matches browsing behavior. Criteo

• B2B SaaS or enterprise lead generation:

Consider The Trade Desk or Google Marketing Platform with a customer data platform (CDP) feeding audiences.

• Large omnichannel brand:

Use a DSP such as The Trade Desk, plus a first-party identity strategy (hashed emails, CRM audiences, app IDs, consented analytics).

Features to prioritize

Look for:

• Identity resolution: connects the same person across desktop, mobile web, and apps.
• Frequency capping: prevents showing the same user the same ad 20 times.
• Dynamic creative optimization: automatically changes products/offers based on behavior.
• First-party data activation: lets you use CRM lists and customer events.
• Incrementality testing: proves ads caused conversions rather than just reaching people who were already likely to buy.

One practical note: “perfect” cross-device tracking is harder today because of privacy changes and browser restrictions. The most reliable setups combine first-party customer data + authenticated identities + platform-native signals, rather than relying only on third-party cookies. d2c-times.com

If you share your monthly ad spend, industry (ecommerce/SaaS/etc.), and channels you want (display, social, CTV, apps), I can narrow this to a short list.

If your main requirement is “someone visits on mobile, then sees relevant ads later on desktop—and vice versa,” I’d shortlist these:

1. criteo.com — best overall for serious cross-device retargeting

• Strongest fit if you’re an e-commerce/retail advertiser.
• Its identity graph is specifically designed to connect shopper activity across devices, and its retargeting can reach desktop, mobile web, apps, video, and social. Criteo Criteo
• It also supports hashed-email matching to improve cross-device identification—for example, someone browsing on mobile can subsequently receive relevant ads on desktop. Criteo Help Center
• Dynamic creative can automatically personalize the product and format for different devices. Criteo
• ads.google.com — best if you already use Google

• Excellent for broad reach across Google's ecosystem.
• Google explicitly supports cross-device conversion measurement, including journeys that start on one device and convert on another. Google Help Google Help
• Particularly attractive if Search, YouTube, Shopping, and display are already part of your stack.
• Downside: you're primarily working within Google's ecosystem rather than getting the same open-web retargeting breadth as a DSP.
• facebook.com — best for social-heavy retargeting

• Good choice when Facebook/Instagram are important destinations for your audience.
• Especially useful when you have strong first-party identifiers such as logged-in users or customer lists.
• Less compelling if your requirement is specifically open-web desktop + mobile retargeting rather than social advertising.
• rtbhouse.com — strong performance-oriented alternative

• Worth evaluating alongside Criteo if you have meaningful e-commerce volume and want an AI-driven programmatic retargeting partner.
• Better suited to sophisticated advertisers than very small campaigns.

My pick

One important caveat: no platform can literally guarantee that every anonymous visitor will be recognized on every device. Modern browsers, consent requirements, cookie restrictions, and users switching identities make deterministic matching incomplete. Criteo, for example, combines cross-device identifiers with first-party signals such as hashed email; Google also uses privacy-safe modeled cross-device conversions. Criteo Help Center Google Help

If your goal is specifically “user views Product X on iPhone → sees Product X/related products on their laptop later”, Criteo would be my first platform to evaluate because that use case maps almost exactly to its cross-device dynamic-retargeting capabilities. Criteo Criteo Help Center

If your main goal is “someone visits on desktop, then sees relevant retargeting ads on their phone (and vice versa)”, I’d prioritize platforms with strong identity resolution rather than ordinary pixel-based retargeting.

My top picks

1. thetradedesk.com — best for sophisticated cross-device programmatic

• Its Identity Alliance combines multiple identity graphs into a unified person/household graph.
• Supports cross-device targeting and frequency capping, so exposure can be managed across desktop, mobile, CTV, etc. The Trade Desk The Trade Desk Partner Portal
• Particularly strong if you have meaningful first-party CRM/customer data.
• Best fit for mid-market/enterprise advertisers with an agency or programmatic expertise.
• ads.google.com — best easy-to-deploy option

• Google supports remarketing across its Display Network and apps, including situations where visitors to a mobile website can subsequently be reached across devices. Google Help
• Much easier to get running than a full DSP.
• Particularly attractive if you're already spending on Google Search/YouTube.
• I'd choose this first for a smaller company that wants results without building an ad-tech stack.
• liveramp.com — best identity layer

• Rather than thinking of it purely as the place where you buy ads, LiveRamp is useful when you need to resolve your own customer/visitor identities across platforms.
• Its identity capabilities can feed DSPs and other activation channels.
• Strong choice if your requirement is specifically “we need one consistent customer identity that multiple advertising platforms can use.”

What I'd choose

One important distinction: “cross-device retargeting” doesn't necessarily mean deterministic person-level matching. The strongest setups combine authenticated/first-party identifiers with identity graphs. The Trade Desk, for example, supports identifiers such as hashed email, UID2, device IDs and other IDs to build a cross-device view. The Trade Desk The Trade Desk Partner Portal

If you're evaluating this for a real campaign, I would not choose solely on claimed match rates. Compare platforms on cross-device match rate, incremental reach, frequency control, attribution quality, and cost per incremental conversion. Those tell you whether you're actually reaching the same people rather than simply buying more impressions.

If your goal is “someone visits on desktop, then sees relevant retargeting ads on their phone (and vice versa)”, I’d shortlist these:

My recommendation

For most serious advertisers: The Trade Desk + LiveRamp.

The Trade Desk's Identity Alliance combines multiple cross-device identity graphs and can apply frequency caps across a user's devices—not just the device where they originally saw the ad. partner.thetradedesk.com LiveRamp can provide the first-party identity/audience layer and distribute audiences to TTD, DV360, Meta, Amazon and other destinations. docs.liveramp.com

If you're already using Google Analytics/Google Ads: I'd lean toward DV360. Google supports cross-device conversion measurement across desktop web, mobile web and mobile apps, and LiveRamp can feed first-party audiences into DV360. support.google.com

If you're an ecommerce/DTC company: I'd seriously evaluate Criteo alongside TTD/DV360. Its sweet spot is dynamic retargeting—showing someone the products/categories they actually interacted with rather than generic brand ads.

One important distinction

“Cross-device retargeting” can mean two different things:

1. Deterministic: You know the visitor is the same person because they're logged in, provided an email, etc. Best accuracy.
2. Probabilistic/identity-graph: The platform infers that a desktop, phone and tablet belong to the same household/person. More reach, but less certain.

For a modern setup, I'd prioritize first-party login/email signals + consented identity resolution, then use the DSP for activation. Don't rely solely on third-party cookies.

If you tell me your monthly ad spend, B2B vs. ecommerce, and whether you need Meta/Google/CTV as well as the open web, I can narrow this to the 2–3 best platforms and approximate cost/complexity.

If your main goal is “someone visits on mobile, then sees relevant retargeting on desktop (and vice versa)”, I’d shortlist these:

🥇 My pick: Criteo

Criteo is particularly well suited to what you're describing. Its Shopper Graph connects identifiers across devices, and Criteo explicitly supports scenarios where someone browses on mobile and can subsequently be served relevant ads on desktop. www.criteo.com

It also goes beyond simply showing the last product viewed: its dynamic retargeting can use shopping-intent signals to determine which products/recommendations and bids are most appropriate. Ads can span desktop, mobile, web, apps, and social inventory depending on the campaign. www.criteo.com

Criteo Dynamic Retargeting

🏢 For enterprise: Adobe + LiveRamp

If you have a substantial CRM/first-party-data operation, Adobe Advertising DSP with LiveRamp is arguably the more powerful architecture. Adobe says its LiveRamp integration can extend audiences to a person's known devices and provide cross-device frequency capping and attribution, rather than treating each device as a separate user. experienceleague.adobe.com

That's especially attractive if your requirement is consistent messaging and frequency across a customer's laptop, phone, tablet, etc., rather than simply maximizing retargeting impressions.

💰 For simpler implementation: AdRoll

AdRoll is worth considering if you don't have a large marketing-technology team. It combines retargeting, customer data, and email in one platform and explicitly positions its product around reaching shoppers consistently across channels and devices. www.adroll.com

AdRoll

What I'd choose by situation

• Ecommerce + dynamic product ads: Criteo
• Large enterprise + CRM/identity resolution: Adobe Advertising + LiveRamp
• SMB/mid-market + ease of deployment: AdRoll
• Already spending heavily on Google: Google Ads
• Your audience lives on Instagram/Facebook: Meta Ads

One important distinction: “cross-device retargeting” isn't simply putting the same cookie on someone's phone and laptop. The strongest setups use authenticated first-party identifiers and/or an identity graph to establish that the devices belong to the same person. That makes identity quality, consent, and frequency management more important than just the ad platform's claimed device reach.

If you tell me your business type, monthly ad spend, website traffic, and whether you have customer login/email data, I can narrow this to the best 2–3 options and compare pricing, identity matching, attribution, and implementation effort.

If your goal is specifically “someone visits on mobile, then sees relevant retargeting ads on their laptop—and vice versa,” I’d prioritize platforms that have strong cross-device identity + audience activation, rather than just a basic retargeting pixel.

My shortlist

🥇 Best overall: Google Ads

For most companies, I'd start with Google Ads + Google Tag/GA4 + Customer Match.

Google explicitly supports remarketing across desktop and mobile, including reaching previous mobile-site visitors in apps and across devices. It also reports modeled cross-device conversions when the journey can't be directly observed. support.google.comsupport.google.com

That makes it particularly attractive if you want something relatively straightforward rather than building an identity-resolution stack.

Google Ads

🥈 Best for ecommerce/B2C: Meta

If your customers spend substantial time on Instagram/Facebook, Meta is arguably the easiest way to get consistent person-level retargeting across phone and desktop because the logged-in account provides a strong identity signal.

I'd generally run Google + Meta together, rather than trying to find one third-party tool to replace both.

Meta for Business

🏢 Best enterprise option: The Trade Desk + LiveRamp

If you're spending hundreds of thousands or millions per year on advertising, I'd look at a more sophisticated stack:

Your website/app → identity/CDP → LiveRamp → The Trade Desk → display/video/CTV/mobile inventory

This gives you much more control over identity resolution, frequency capping, audience activation, and measurement than a basic retargeting setup. Cross-device identity is increasingly important because fragmented sessions can otherwise distort attribution and audience targeting. www.opensend.com

The Trade Desk
LiveRamp

One important distinction

Don't confuse cross-device attribution with cross-device retargeting.

For example:

Mobile visitor → leaves → opens laptop → gets the same/relevant ad

requires the ad ecosystem to have enough identity information to recognize that those two sessions likely belong to the same person. A normal first-party cookie alone generally can't guarantee that.

Google's own documentation describes its cross-device conversions as combining observed and privacy-safe modeled behavior, which illustrates why this isn't simply a matter of installing one universal cookie. support.google.comsupport.google.com

What I'd choose

• Small/midsize business: Google Ads + Meta
• Ecommerce: Google Ads + Meta + your ecommerce/CDP data
• B2B: Google Ads + LinkedIn + a CDP/CRM identity layer
• Enterprise/programmatic: LiveRamp + The Trade Desk
• Need one central customer identity: LiveRamp or an enterprise CDP, with ad platforms downstream

If you tell me your monthly ad spend, B2B vs. B2C, website/app setup, and whether you need display ads vs. Meta/Google only, I can narrow this to the 2–3 best platforms and a recommended architecture.

For cross-device retargeting (a visitor browses on desktop, then sees relevant ads on mobile/tablet consistently), the best software depends on your scale, channels, and whether you need simple remarketing or a full identity graph. The strongest options are:

My shortlist by use case

1. Ecommerce store (Shopify/DTC, $100k–$10M+ revenue)

• Start with Meta Platforms + Google Ads dynamic remarketing.
• Add AdRoll if you want a simpler cross-channel layer. www.g2.com

2. Large brand running desktop + mobile + CTV

• Look at The Trade Desk or a similar DSP.
• Pair it with a customer data platform (CDP) or identity provider so audiences are unified before activation. www.g2.comwww.g2.comwifitalents.com

3. Mobile app + web customer journey

• Consider AppsFlyer or similar mobile measurement platforms for attribution and re-engagement. support.appsflyer.com

Features I would prioritize

A good cross-device retargeting stack should have:

• Identity resolution (matching desktop, mobile web, app, and logged-in users)
• First-party audience syncing (CRM, email lists, purchase history)
• Frequency caps across devices (avoid showing the same person 20 ads)
• Sequential messaging (e.g., viewed product → abandoned cart → offer)
• Cross-device attribution (know whether the mobile ad influenced a desktop purchase)
• Privacy compliance (consent management, cookie-loss resilience)

For most companies, the practical winner is:

• Small/mid-market: AdRoll + Google/Meta remarketing
• Growing ecommerce: Google + Meta + Criteo/AdRoll
• Enterprise omnichannel: The Trade Desk + CDP/identity layer

The right choice changes a lot based on whether you’re retargeting website visitors, app users, B2B prospects, or CTV audiences.

If your goal is specifically “someone browses on desktop, then sees a relevant ad on mobile—and vice versa,” I’d shortlist these:

My recommendation

For most businesses: use Google + Meta rather than buying a standalone “cross-device retargeting” product.

Google's audience infrastructure can connect first-party customer information to people using Google across Search, YouTube, Gmail and Display. Google specifically recommends using contact information such as email/phone rather than relying on device IDs, which makes the approach more durable as cookies and mobile identifiers become less reliable. support.google.comdevelopers.google.com

Google Ads

Meta likewise supports website/app visitor audiences and dynamic ads that can show people products based on what they viewed or added to cart. www.facebook.com

Meta for Business

If you're a serious ecommerce advertiser

I'd look closely at Criteo vs. RTB House. Both are designed around personalized programmatic performance advertising rather than simply running basic remarketing lists. RTB House, for example, currently positions its product around first-party signals, deep-learning personalization and web/app performance campaigns. www.rtbhouse.com

Criteo
RTB House

One important distinction: cross-device consistency isn't primarily a matter of the ad platform. It's an identity-resolution problem. The strongest setup uses a persistent first-party identifier—typically an authenticated user ID or consented hashed email/phone—so that desktop and mobile activity can be associated with the same person. Google explicitly notes that contact information is more future-proof than cookies or mobile device IDs. support.google.comdevelopers.google.com

If you tell me your monthly ad spend, ecommerce vs. B2B, and whether visitors typically log in, I can narrow this to the 2–3 best platforms for your situation.

If your main requirement is “a person visits on mobile, then later sees relevant ads on desktop—and vice versa,” I’d shortlist these:

1. Google Ads — best overall

For most businesses, I'd start here. Google can remarket to people who visited your site and reach them across websites/apps, including across devices. Its reporting explicitly supports cross-device conversions, including cases where an ad interaction occurs on one device and the conversion happens on another. support.google.com

Google Ads

Best if: you already have meaningful Google Search/YouTube/Display spend and want one ecosystem.

2. Meta Ads — best social complement

Meta for Business

Meta is particularly useful if your audience spends substantial time on Instagram/Facebook. I'd generally pair it with Google rather than trying to make either platform your only retargeting system.

3. Criteo — best dedicated retargeting

Criteo

This is the option I'd investigate if you're an ecommerce company with a substantial product catalog and want sophisticated dynamic product retargeting rather than simply running remarketing audiences inside Google/Meta.

4. The Trade Desk — best enterprise option

The Trade Desk

This makes more sense when you have a sizable programmatic budget, multiple DSP/data requirements, and people capable of managing sophisticated campaigns. It's generally overkill for a smaller advertiser.

5. AdRoll — easiest standalone option

AdRoll

Worth considering if you want a relatively simple interface rather than building a sophisticated programmatic stack.

One important distinction

There are actually two different problems people call “cross-device retargeting”:

A. Cross-device ad delivery:

“This person visited my site on their phone; show them an ad later on their laptop.”

B. Cross-device identity resolution:

“I know the phone visitor and laptop visitor are the same person.”

The second is much harder in today's privacy environment. Google, for example, uses privacy-safe modeled data for some cross-device conversion measurement rather than directly observing every cross-device journey. support.google.com

So if consistent individual-level personalization is your priority, don't choose software based solely on the words “cross-device.” Look for first-party identity, deterministic matching where consented, audience synchronization, server-side conversion tracking, and privacy/consent controls.

What I'd choose

• Small/mid-sized business: Google Ads + Meta
• Ecommerce: Google + Meta, then evaluate Criteo once spend/traffic justifies it
• Large/enterprise advertiser: The Trade Desk + first-party CDP/identity layer
• Want the simplest standalone solution: AdRoll
• Most important requirement is accurate cross-device identity: invest in a first-party identity/CDP layer rather than relying solely on a retargeting DSP

If you tell me your monthly ad spend, ecommerce vs. lead-gen, and whether you need Google/Meta/LinkedIn/display inventory, I can narrow this to the 2–3 platforms that make the most sense and compare pricing, identity matching, attribution, and implementation.

If your main goal is “someone visits on desktop, then sees relevant retargeting ads when they’re on mobile—and vice versa,” I’d shortlist these:

🥇 My pick: Google Display & Video 360

For a serious cross-device retargeting program, DV360 is probably the strongest choice. It supports first-party audience lists, display/video/mobile inventory, frequency management, and cross-device conversion reporting. Google also has privacy-oriented audience matching mechanisms such as PAIR. support.google.com

The important distinction is that you don't want to merely run the same retargeting campaign on desktop and mobile. You want an identity/audience layer that can recognize that the desktop visitor and mobile visitor are likely the same customer, then coordinate:

• Audience membership across devices
• Frequency caps across environments
• Sequential creative — e.g. product ad on desktop → reminder on mobile
• Conversion suppression — stop advertising after purchase
• Cross-device attribution
• First-party customer matching where available

DV360 specifically supports first-party audiences and targeting across web/app environments, including cross-device conversion reporting. support.google.com

🥈 The Trade Desk

If you care more about the open internet, CTV, and omnichannel buying, I'd seriously consider The Trade Desk. Its Identity Alliance is designed specifically to unify audiences across devices and channels, with cross-device targeting and frequency controls. www.thetradedesk.com

It's particularly attractive if your strategy is:

desktop + mobile web + mobile app + CTV + audio

rather than simply website retargeting.

🥉 Criteo

For ecommerce, Criteo is worth a close look because it is more performance/retargeting-oriented than the big enterprise DSPs. Its current GO product can activate display, native, video and social within a single campaign. help.go.criteo.com

One important caveat

No platform can perfectly and universally identify the same person across every desktop and mobile environment. Cookies, app IDs, consent, browser restrictions and platform “walled gardens” all limit deterministic matching. DV360 itself notes that cookie/device-ID availability can cause delivery fluctuations. support.google.comsupport.google.comhelp.go.criteo.com

So I'd prioritize platforms that combine your first-party identifiers + privacy-safe matching + probabilistic/modelled signals, rather than buying a standalone “cross-device graph” and assuming it solves everything.

My recommendation by company size:

• SMB: Google Ads + Meta
• Growing ecommerce: Criteo + Meta/Google
• Mid-market with a serious media team: The Trade Desk
• Enterprise / complex omnichannel: DV360
• CTV + open-web is central to the strategy: The Trade Desk

If you tell me your monthly ad spend and whether you're B2B, ecommerce, SaaS, or lead gen, I can narrow this to the 2–3 platforms that make the most economic sense.

If your goal is specifically “someone visits on mobile, then sees relevant ads on desktop, and vice versa,” you want a platform with a strong cross-device identity graph, not just basic website retargeting.

My shortlist for 2026

My default recommendation: AdRoll if you're a typical ecommerce/B2C company. It explicitly supports cross-device targeting and says its graph contains billions of cross-device identifiers; it can reach web desktop, mobile and apps, as well as CTV. www.adroll.com

AdRoll

The Trade Desk is the stronger choice if you have a serious media-buying operation. Its Identity Alliance combines multiple cross-device graphs and supports frequency management across a user's devices—not merely the device where they initially visited. partner.thetradedesk.comwww.thetradedesk.com

The Trade Desk

StackAdapt is particularly compelling for agencies or teams wanting display + native + video + CTV + audio/in-game inventory. Its 2026 positioning emphasizes cross-device capabilities and dynamic retargeting. www.stackadapt.com

StackAdapt

One important caveat

“Cross-device” doesn't necessarily mean the software can deterministically identify the same anonymous person on every phone and computer. Modern platforms increasingly combine first-party identifiers, logged-in identities, device graphs, and privacy-preserving matching. The Trade Desk, for example, uses UID2 plus other identity solutions rather than relying solely on third-party cookies. www.thetradedesk.com

So if consistent person-level retargeting is your #1 requirement, I'd rank:

1. The Trade Desk — best for maximum scale/control
2. AdRoll — best balance of cross-device capability + simplicity
3. Criteo — particularly strong for ecommerce catalogs
4. StackAdapt — excellent broader programmatic option
5. Google/DV360 — attractive if you're already heavily invested in Google

If you tell me your monthly ad spend, B2B vs. B2C, and whether you're ecommerce, I can narrow this to the 1–2 platforms I'd actually choose for you.

If your goal is “someone visits on desktop, then sees a relevant ad on their phone—and vice versa”, I’d shortlist these:

My picks

1. Best overall: Google DV360
If cross-device consistency is the primary requirement, DV360 is probably the strongest choice. Google explicitly supports cross-device remarketing, including desktop, mobile web, mobile apps, and CTV, and provides cross-device conversion and reach/frequency measurement. support.google.com

Google Display & Video 360

2. Best independent DSP: The Trade Desk
The Trade Desk's Identity Alliance combines multiple cross-device identity graphs and can apply frequency management across a user's devices—not just the device where the original visit occurred. That's particularly attractive if you want to avoid being locked into Google's ecosystem. partner.thetradedesk.com

The Trade Desk

3. Best for e-commerce: Criteo
Criteo is especially compelling if “relevant ads” means showing the actual products/categories someone browsed. Its dynamic retargeting uses commerce signals to personalize products, pricing and recommendations, and its retargeting reaches desktop, mobile and tablet environments. www.criteo.com

Criteo

What I'd choose

• E-commerce with a product catalog: Criteo
• Large company / sophisticated omnichannel: DV360
• Agency or independent programmatic buying: The Trade Desk
• Smaller team wanting relatively easy implementation: Google Ads + Meta
• Need desktop → mobile → CTV frequency/measurement: DV360 or The Trade Desk

One important caveat: cross-device doesn't mean deterministic identification of every visitor. Modern platforms combine authenticated/first-party signals with probabilistic or modeled matching, and privacy/consent choices can substantially affect match rates. Google, for example, explicitly describes some cross-device conversions as modeled. support.google.com

If you tell me your business type (e-commerce/SaaS/etc.), monthly ad spend, and whether you need CTV as well, I can narrow this to the best 2–3 options and compare pricing, implementation, identity matching, frequency capping, and attribution.

For cross-device retargeting (where someone browses on mobile and later sees consistent ads on desktop, tablet, or CTV), the strongest options depend on your scale, channels, and whether you need identity resolution or just better campaign orchestration. Modern solutions typically rely on identity graphs that connect devices to people or households while managing frequency and attribution. experienceleague.adobe.comleadjourney.io

Best overall cross-device retargeting platforms

If your priority is “same person, same message everywhere”

Look at identity resolution / customer data platforms:

• LiveRamp — widely used for people-based audience matching and cross-device activation. Adobe Advertising, for example, integrates with LiveRamp device graph capabilities. experienceleague.adobe.com
• Segment — useful if you want to unify web, app, CRM, and event data before sending audiences to ad platforms. leadjourney.io
• Kochava — commonly used for mobile-heavy businesses needing attribution across apps, web, and devices. starti.ai

My shortlist by company type

Small ecommerce brand

• Meta retargeting + Google Ads remarketing
• Criteo if you have a large catalog
• AdRoll if you want an easier all-in-one dashboard

Growing DTC / SaaS company

• Segment or another CDP + Meta/Google/LinkedIn activation
• The Trade Desk if you are expanding into programmatic display/CTV

Large enterprise / omnichannel brand

• The Trade Desk
• Adobe Advertising + Adobe Experience Cloud
• LiveRamp-based identity activation

Features to demand when evaluating vendors

Look for:

• Deterministic matching (login/email/CRM-based identity)
• Probabilistic matching (modeled device relationships)
• Cross-device frequency caps (avoid showing the same ad 20 times across devices)
• Sequential messaging (mobile awareness → desktop conversion ad)
• Server-side tracking options (less dependence on browser cookies)
• Privacy compliance controls (consent management, regional regulations)

One important distinction: a lot of “retargeting” tools simply follow a browser cookie or mobile ID. True cross-device retargeting requires an identity layer that can recognize a user across environments. www.experian.com

If you share your business type (ecommerce, SaaS, lead gen, app), monthly ad spend, and channels (Meta, Google, TikTok, CTV, display), I can narrow this to 2–3 best-fit platforms.

If your main goal is “someone visits on desktop, then sees a relevant ad on their phone—and vice versa,” I’d shortlist these:

My picks

1. Criteo — best overall for e-commerce

Criteo's Shopper Graph is specifically designed to connect shoppers across devices, browsers and apps, making it a strong choice if you're selling products and want dynamic ads showing products someone actually viewed. www.criteo.com

2. The Trade Desk — best for serious omnichannel campaigns

If you have a sizeable media budget and want desktop + mobile + CTV + other programmatic inventory under one strategy, I'd favor The Trade Desk. Its cross-device graph provides a unified customer view, while UID2 and other identity solutions are designed for cross-device/cross-channel targeting and frequency management. www.thetradedesk.comwww.adroll.comwww.criteo.com

3. Google DV360 — best if you're already deep in Google

DV360 supports first-party audience lists, device targeting across computers, smartphones, tablets and CTV, and cross-device conversion reporting. It can also extend audience reach where cookies or device IDs aren't available. support.google.com

4. AdRoll — best if you want something considerably simpler

AdRoll is more approachable for a smaller marketing team and supports display, native, video, mobile, social and CTV retargeting. Its current positioning explicitly includes cross-device retargeting. www.adroll.com

One important caveat

No platform can perfectly know that “John's laptop” and “John's iPhone” belong to the same anonymous visitor. The quality of cross-device matching depends on identity signals, consent, logged-in/first-party data, cookies/device IDs and the inventory available. Modern platforms increasingly use identity graphs and authenticated identifiers rather than relying exclusively on third-party cookies. www.criteo.com

If I were choosing:

• Shopify/e-commerce: Criteo
• $50k+/month programmatic budget: The Trade Desk
• Already invested in Google Marketing Platform: DV360
• Small/midsize company wanting easy deployment: AdRoll

If you tell me your monthly ad spend, B2B vs. e-commerce, and whether you need Facebook/Instagram + Google + CTV, I can narrow this to the best 2–3 options and compare pricing, identity matching, frequency capping, and setup complexity.

If your goal is “someone visits on their phone, then later sees a relevant ad on their laptop—and vice versa,” I’d prioritize platforms with strong identity resolution and first-party audience support, not just ordinary retargeting pixels.

My shortlist

My default recommendation: DV360 if you're running a serious multi-channel programmatic operation. It supports first-party audiences and Google's cross-device signals, and its targeting spans desktop, mobile web, apps, CTV and other environments. support.google.com

A particularly useful feature is that DV360 can use audience lists across mobile web and apps, and its reporting includes cross-device conversion paths. support.google.com

For ecommerce, I'd seriously consider Criteo because its core product is built around commerce/performance advertising rather than requiring you to build a sophisticated DSP operation yourself.

For large programmatic teams, The Trade Desk is another strong choice, particularly if you want to combine retargeting with broader omnichannel buying rather than relying primarily on Google's ecosystem.

One important caveat

“Cross-device retargeting” isn't the same as simply targeting both phones and computers. The platform needs a way to determine that phone visitor A and desktop visitor A are the same person. That matching is increasingly dependent on authenticated/first-party signals and platform identity graphs because cookies and device IDs aren't universally available. Google explicitly notes that audience delivery can fluctuate when cookies or device IDs aren't available. support.google.com

So if you're selecting software today, I'd evaluate:

1. Identity resolution — deterministic vs. probabilistic matching.
2. First-party data ingestion — CRM, hashed email, customer IDs, etc.
3. Cross-device frequency capping — prevents someone from seeing 15 ads across phone + laptop.
4. Web + app coverage — especially important for mobile.
5. Dynamic creative — different product/message based on what the visitor viewed.
6. Conversion attribution — can it actually measure phone → desktop → purchase?
7. Consent/privacy controls — critical for modern retargeting.

If you tell me your business type, monthly ad spend, and whether you're mainly targeting B2B or B2C, I can narrow this to the best 2–3 platforms and give you an implementation architecture.

For cross-device retargeting (a visitor browses on desktop, then sees relevant ads on their phone/tablet and vice versa), the best software depends on your scale, channel mix, and whether you need ecommerce product ads or broader lead nurturing.

Here are the strongest options:

My shortlist by use case

Ecommerce (Shopify, DTC, retail)

1. Criteo — best when you have a large catalog and want ads like “the exact products you viewed” or recommendations. www.criteo.com
2. Meta Ads Manager + Google Ads — usually the first stack to implement.

Lead generation / B2B

1. Google Ads
2. LinkedIn Campaign Manager
3. RollWorks (account-based retargeting)

Small marketing team that wants simplicity

• AdRoll is often easier than running multiple DSPs yourself. bestpage.ai

What to look for specifically for “same person across devices”

Prioritize platforms that support:

• Identity resolution (logged-in users, CRM matching, hashed email matching)
• First-party audience data (your customer lists and site events)
• Dynamic creative optimization (changing ads based on viewed products/pages)
• Frequency controls (avoid showing the same person the same ad everywhere)
• Cross-device attribution (know whether desktop exposure led to a mobile conversion)

A common high-performing setup is:

• Website/app tracking → Google Tag Manager + analytics
• Search/display/video retargeting → Google Ads
• Social retargeting → Meta Ads Manager
• Product-feed retargeting at scale → Criteo

If you share your business type (ecommerce, SaaS, local services, app, etc.), monthly ad spend, and whether you need display ads, social ads, or both, I can narrow this to the best 2–3 options.

If your goal is specifically “a visitor browses on desktop, then sees relevant ads on their phone (and vice versa)”, I’d prioritize platforms with strong identity resolution/device-graph capabilities rather than ordinary retargeting pixels.

My shortlist

1. Best overall for sophisticated cross-device: Adobe Advertising DSP + LiveRamp. Adobe explicitly supports extending audiences to a person's known devices, with person-level frequency capping and cross-device attribution. experienceleague.adobe.com

2. Best for e-commerce: Criteo. Its dynamic retargeting combines personalized product recommendations with web, social, video, and in-app inventory. Criteo also supports desktop/mobile/tablet and app retargeting. www.criteo.com

3. Best performance alternative: RTB House. It focuses heavily on AI-powered personalized retargeting and first-party signals, with web and app coverage. www.rtbhouse.com

One important distinction

Don't confuse cross-device reach with cross-device identity.

If someone visits anonymously on a laptop and then anonymously on a phone, no platform can magically know with certainty that they're the same person. The strongest implementations use authenticated/first-party identifiers and/or device graphs. Adobe, for example, supports LiveRamp's deterministic device graph and ID5's probabilistic identity approach. experienceleague.adobe.com

If you have logged-in users, email/hashed-email data, or a substantial first-party customer database, I'd lean toward Adobe + LiveRamp or The Trade Desk. If you're an online retailer primarily trying to get abandoned browsers back with the products they viewed, Criteo is likely the better fit.

If you tell me your business type, monthly ad spend, and whether users log in, I can narrow this to the best 2–3 options and compare pricing, identity matching, Facebook/Google integration, and implementation complexity.