ChatGPT answers, unedited

If your goal is one audience/retargeting layer that coordinates email with paid media, I’d shortlist these:

• Customer.io — particularly strong if you want behavioral segments to drive both email and advertising. It can sync segments to Google Ads, Meta/Facebook/Instagram, YouTube, and other destinations; its current integration directory also lists Criteo, Pinterest, TikTok, Bing, and X destinations. Customer.io Customer.io
• Klaviyo — a strong fit if your email provider is already Klaviyo, especially for ecommerce. It can sync lists/segments into Meta, Google, TikTok, and Pinterest for custom/retargeting and lookalike audiences. Klaviyo Help Center academy.klaviyo.com

My recommendation

If you already use Customer.io for email, use Customer.io's ad-audience synchronization rather than adding another retargeting platform. You can create lifecycle/behavioral segments once—for example:

• Viewed product but didn't purchase → Meta + Google retargeting
• Abandoned cart → email + paid retargeting
• Purchased recently → suppress from acquisition ads
• High-value customers → retention campaigns + lookalike audiences

Customer.io automatically synchronizes the segments to the ad networks, rather than requiring recurring CSV exports. Customer.io

If you tell me which email provider you use (Klaviyo, HubSpot, Mailchimp, Customer.io, Braze, etc.) and which ad networks (Meta, Google, TikTok, LinkedIn, Criteo, etc.), I can narrow this to the most appropriate architecture and integration.

If your goal is one audience/segmentation layer driving both email and paid retargeting, I’d shortlist these:

1. Klaviyo — strong fit for ecommerce

If your email provider is already Klaviyo, this is probably the most straightforward architecture. Klaviyo can sync lists/segments to Meta Ads and Google Ads, allowing the same behavioral segments used for email to become ad audiences. It also supports integrations with TikTok and Pinterest. Klaviyo Help Center Klaviyo Help Center Klaviyo

A useful campaign could look like:

• Browsed product, no purchase → abandoned-browse email + Meta/Google retargeting
• Started checkout, no purchase → cart email + retargeting ads
• Purchased → suppress from acquisition/retargeting + move into cross-sell email/ad audience
• High-value customers → email nurture + lookalike audience

One caveat: Meta and Google can take time to process audience updates, and matched audience sizes will generally be smaller than your source email segments. Klaviyo Help Center Klaviyo Help Center

2. Customer.io — better if you need broader orchestration

Customer.io is worth considering if you're not tied to a particular email platform or need more sophisticated event-based segmentation. Its Ad Audiences feature synchronizes segments with Google and Meta, and its integration directory also includes destinations such as TikTok, Pinterest, Criteo Audiences, and Bing Ads. Customer.io Customer.io

It also hashes email/mobile identifiers before sending audience data to ad networks. Customer.io

My practical recommendation

I wouldn't add a separate "retargeting platform" unless you have a specific need for cross-network media buying/optimization beyond audience synchronization. In many setups, the email/CDP layer should own segmentation, while Meta/Google/etc. execute the advertising.

If you tell me which email provider you use (Klaviyo, HubSpot, Braze, Salesforce, Mailchimp, etc.) and which ad networks you need, I can narrow this to the most appropriate architecture and integrations.

For a combined email + paid retargeting strategy, I’d look at platforms that can unify your first-party customer segments with ad audiences (Meta, Google, programmatic, etc.) rather than treating email and ads as separate channels.

Here are strong options depending on your stack:

My shortlist by scenario

• Shopify / ecommerce + Klaviyo: Start with Klaviyo’s audience sync, or add AdRoll if you want broader display retargeting.
• B2B SaaS + HubSpot/Salesforce-style CRM: Consider Customer.io or a CDP-based approach (such as Listrak/D·engage depending on scale).
• Large customer database + many channels: Use a CDP/lifecycle platform that can manage audiences centrally.
• Need “email behavior → ads” automation: Customer.io, Listrak, and AdRoll are closer to that workflow. Listrak Customer.io

Capabilities I’d require before choosing

1. Two-way audience syncing

• Email segments → Meta Custom Audiences
• Email segments → Google Customer Match
• Ad engagement → lifecycle journeys
• Behavior-based triggers

• Cart abandonment
• Product viewers
• Trial users
• Inactive customers
• High-value customers
• Suppression controls

• Stop showing acquisition ads to existing buyers
• Exclude unsubscribed users
• Prevent overspending on converted users
• Measurement

• Revenue attribution across email + ads
• Incremental lift testing
• Cohort reporting

If you tell me your email provider (Klaviyo, HubSpot, Mailchimp, Salesforce Marketing Cloud, etc.), ad networks (Meta, Google, LinkedIn, TikTok, programmatic), and whether you’re B2B or ecommerce, I can narrow this to 2–3 best-fit solutions.

If your email provider is Klaviyo, I’d recommend using Klaviyo itself as the audience/retargeting hub, rather than adding a separate retargeting platform.

Klaviyo can sync the same first-party segments used for email into Meta, Google Ads, TikTok, Pinterest, and Criteo, letting you coordinate email and paid retargeting around the same customer state. Klaviyo Klaviyo Academy

Recommended setup

• Klaviyo — source of truth for customer segments.
• Meta Ads — retarget site visitors, cart abandoners, lapsed customers, etc. Klaviyo can sync lists/segments into Meta Custom Audiences. Klaviyo Help Center
• Google Ads — sync Klaviyo segments into Google audiences for retargeting and suppression. Klaviyo Help Center
• TikTok / Pinterest / Criteo — add these if they matter to your acquisition mix. Klaviyo

The important advantage is cross-channel orchestration. For example:

Customer abandons cart → Klaviyo sends abandoned-cart email → same segment gets Meta/Google retargeting → customer purchases → they automatically leave the retargeting segment and enter a post-purchase/cross-sell segment.

Klaviyo specifically supports use cases such as cart-abandoner, winback, re-engagement, cross-sell, and cross-channel audiences. Klaviyo Help Center Klaviyo Help Center

One caveat: audience synchronization isn't necessarily instantaneous. For example, Klaviyo says Meta Custom Audiences can take 24–48 hours to update. Klaviyo Help Center

If you tell me which email provider you use (Klaviyo, HubSpot, Mailchimp, Salesforce Marketing Cloud, etc.) and which ad networks you need (Meta, Google, TikTok, LinkedIn, Criteo), I can recommend the best specific architecture and 2–3 vendor alternatives.

If your goal is one retargeting strategy that connects email audiences with multiple ad networks, I’d recommend klaviyo.com + its native ad integrations—assuming Klaviyo is your email/CRM provider.

My recommendation: Klaviyo as the audience hub

Klaviyo can sync customer segments into Meta, Google Ads, TikTok, Pinterest, and Criteo, allowing the same first-party audience logic to drive both email and paid campaigns. Klaviyo UK Klaviyo Academy

That enables campaigns such as:

• Cart abandoners: email + Meta/Google retargeting with the same offer.
• Recent purchasers: suppress from acquisition ads and move them into cross-sell email/ad campaigns.
• Lapsed customers: trigger a win-back email and simultaneously retarget them with paid social/display.
• High-value customers: use the segment for retention ads and lookalike acquisition.
• Email-engaged but non-converting users: coordinate email and paid ads rather than treating them as separate audiences.

Klaviyo specifically supports syncing segments to Meta Custom Audiences and Google Audiences, including retargeting and exclusion use cases. Klaviyo Help Center Klaviyo Help Center

If you need stronger cross-network retargeting

I’d also evaluate criteo.com alongside Klaviyo. Criteo explicitly supports CRM/email integrations including Klaviyo, Mailchimp, Bluecore, and HubSpot, and can activate those audiences across its retargeting inventory and social channels. Criteo Criteo

So the architecture I'd favor is:

Email/CRM → Klaviyo segments → Meta + Google + TikTok/Pinterest + Criteo

with your website behavioral data feeding the segmentation layer.

Bottom line: If you're already on Klaviyo, start there rather than buying a separate retargeting platform. Add Criteo if you need materially broader programmatic/open-web retargeting or more sophisticated commerce-focused optimization.

If you tell me which email provider you use and which ad networks you need (e.g., HubSpot + Meta + Google + LinkedIn), I can narrow this to 2–3 specific platforms and compare integration depth, audience syncing, attribution, and likely cost.

If your goal is one audience/segmentation layer driving coordinated email + paid retargeting, I’d shortlist these:

My top recommendation: Customer.io

customer.io is particularly strong if you want a dedicated cross-channel orchestration layer rather than simply syncing an email list to ads.

• Email + ads: Customer.io segments can be synchronized directly to Meta/Facebook, Instagram, Google Ads, and YouTube audiences. Customer.io Customer.io
• Behavioral retargeting: You can build audiences from behaviors and lifecycle stages, then use the same segments for messaging and paid retargeting. Customer.io
• Broader ad ecosystem: Its integration directory also includes Criteo, Pinterest, TikTok, Bing, and Meta Conversions API, among others. Customer.io
• Automatic syncing: Most ad audiences sync hourly; Google Ads currently has a 24-hour sync interval. Customer.io
• It can also handle exclusion audiences, which is important for preventing existing customers from receiving acquisition ads unnecessarily. Customer.io

Example campaign:
Someone views Product A → receives a Product A email → if they don't purchase, they're added to a Meta/Google retargeting audience → after purchase, they're automatically removed from the retargeting segment and moved into a post-purchase email/ad journey.

If you're already using Klaviyo

Then I would not add another retargeting platform initially. klaviyo.com already syncs lists/segments with Meta and Google Ads and supports integrations with Google, Meta, TikTok, and Pinterest. Klaviyo Help Center Klaviyo Help Center Klaviyo Academy

Quick decision

• Customer.io → best if you want sophisticated lifecycle orchestration across email + ads.
• Klaviyo → best if ecommerce/email is already centered on Klaviyo.
• Dedicated ad-retargeting vendor → worth considering if you need broader programmatic/display inventory beyond the major ad networks.

If you tell me which email provider you're currently using (Klaviyo, HubSpot, Mailchimp, Customer.io, Braze, Salesforce Marketing Cloud, etc.) and which ad networks matter (Meta, Google, TikTok, LinkedIn, Criteo, etc.), I can narrow this to the best 2–3 options and compare integration depth, audience syncing, attribution, and likely implementation effort.

If your goal is one retargeting strategy that coordinates email with paid media, my top recommendation is klaviyo.com—assuming your email provider is already Klaviyo.

Why Klaviyo

• Shared audience segmentation: Build segments such as cart abandoners, recent purchasers, lapsed customers, VIPs, or inactive subscribers once, then use them for both email and ads.
• Meta + Google: Klaviyo can sync those segments to Meta Ads and Google Ads, including retargeting and suppression audiences. Klaviyo Help Center Klaviyo Help Center
• Additional ad networks: Klaviyo also supports audience syncing with TikTok and Pinterest, giving you a broader paid-media layer. Klaviyo Academy Klaviyo SG
• Cross-channel journeys: You can coordinate something like: abandoned cart → email → if no purchase, paid retargeting → if purchase, suppress from ads. Klaviyo specifically supports using the same behavioral segments across email and advertising. Klaviyo Help Center
• First-party data: This is preferable to building your retargeting strategy entirely around browser cookies; Klaviyo's audience integrations use your customer/profile data to create ad audiences. Klaviyo Docs

A practical setup

One caveat: this isn't necessarily a single ad-buying platform. Klaviyo acts more like the customer-data/orchestration layer while Meta, Google, etc. execute the advertising. For example, Google notes that synced audiences can take up to 48 hours to populate/process. Klaviyo Help Center

If you tell me which email provider you use (Klaviyo, HubSpot, Mailchimp, Salesforce Marketing Cloud, Braze, etc.) and which ad networks matter most, I can recommend the best 2–3 solutions and compare them on integration depth, audience sync, automation, attribution, and cost.

If your goal is one retargeting strategy that coordinates email audiences with multiple ad networks, I’d recommend klaviyo.com + AdRoll as the strongest fit—assuming Klaviyo is your email/CRM provider.

My recommendation: Klaviyo + AdRoll

• Klaviyo becomes the customer-data and segmentation layer. Its segments can be synced to Meta, Google, TikTok, Pinterest, and other ad platforms, so the same audiences used for email can drive paid retargeting. Klaviyo Klaviyo Academy
• AdRoll adds a centralized paid-retargeting layer: it can import Klaviyo lists/segments and run campaigns across web, CTV, and social, including Meta, TikTok, and Pinterest. Klaviyo
• This lets you build coordinated journeys such as: - Viewed product → email + display/social ads
• Abandoned cart → abandoned-cart email + retargeting ads
• Purchased → suppress acquisition ads + cross-sell email/ads
• High-LTV customer → VIP email + lookalike acquisition
• Unengaged subscriber → win-back email + paid reactivation

When I'd choose just Klaviyo

If you already have strong in-house ad buying, Klaviyo alone may be better. Its native integrations can sync segments directly to Meta and Google, including suppression audiences and retargeting segments. Klaviyo Help Center Klaviyo Help Center

The big advantage is that your email segmentation and ad audiences remain aligned, rather than maintaining separate audiences in an advertising platform.

Decision

One caveat: don't interpret this as a single campaign literally running identically across every network. Each ad network has its own audience matching, consent, attribution, and optimization rules. For example, Klaviyo notes that Meta audience syncing can take 24–48 hours. Klaviyo Help Center

If you tell me which email provider and ad networks you currently use, I can narrow this to the best 2–3 solutions and compare integration depth, audience syncing, attribution, and likely implementation effort.

If your goal is one audience/segmentation layer powering both email and paid retargeting, I’d shortlist these:

• klaviyo.com — best overall for ecommerce. It can use the same segments for email and ad audiences, with direct integrations for Meta and Google, plus TikTok and Pinterest. For example, a “cart abandoned in 7 days, no purchase” segment can drive both an email flow and matching retargeting ads. Klaviyo Help Center Klaviyo Help Center Klaviyo Academy
• customer.io — best if you need sophisticated behavioral journeys. Customer.io can sync segments to Meta and Google ad audiences, with hourly list automation, while those same behavioral segments can drive email/messaging campaigns. Customer.io Customer.io
• Dedicated retargeting/CDP layer — worth considering if you already have an email provider you like and don't want to replace it. I'd evaluate this route when you need orchestration across many ad networks, stronger identity resolution, or centralized attribution.

My recommendation

Start with Klaviyo if you're ecommerce-focused; Customer.io if you're SaaS/product-led or heavily event-driven.

The campaign architecture I'd use is:

Customer behavior → shared segment → Email + Meta + Google

For example:

• Viewed product, no purchase: email + Meta/Google retargeting
• Abandoned cart: email first, then ads if they don't convert
• Recent purchaser: suppress from acquisition/retargeting ads
• High-value customer: email cross-sell + targeted paid audience
• Lapsed customer: win-back email + paid reactivation

The important part is audience synchronization and suppression, rather than simply running the same creative in every channel. Klaviyo specifically supports using purchase and engagement criteria to retarget or exclude people from Google and Meta campaigns. Klaviyo Help Center Klaviyo Help Center

If you tell me which email provider you currently use (e.g. HubSpot, Mailchimp, Braze, Salesforce Marketing Cloud, Klaviyo), I can recommend the best retargeting stack around it and compare integration depth, ad networks, audience sync, attribution, and approximate cost.

For a combined email + paid retargeting campaign stack, I’d look for a solution that can:

• Sync email audiences/segments into ad networks (Meta, Google, LinkedIn, TikTok, etc.)
• Suppress audiences across channels (e.g., stop showing ads to recent purchasers)
• Trigger coordinated journeys (email + ads after cart abandonment, inactivity, product views)
• Feed ad engagement/conversion signals back into your customer profiles
• Support identity resolution and consent management

Here are the strongest options depending on your stack:

1. HubSpot — best if CRM + lifecycle marketing are central

hubspot.com

Best for: B2B, SaaS, complex sales funnels, teams wanting one customer record.

Strengths:

• Native ad integrations with major networks including Meta, Google, LinkedIn, and TikTok. HubSpot HubSpot Knowledge Base
• Builds audiences from CRM lifecycle stages, email engagement, form activity, and website behavior. KLA Group
• Strong attribution/reporting because campaigns tie back to contacts and deals.

Typical workflow:

• Lead downloads content → enters email nurture
• If they don’t convert → automatically added to LinkedIn/Google/Meta retargeting
• When they become a customer → removed from acquisition ads

Choose this if: your email provider is already HubSpot or your CRM is the source of truth.

2. Klaviyo + ad integrations — best for ecommerce

klaviyo.com

Best for: Shopify/ecommerce brands, DTC, subscription businesses.

Strengths:

• Syncs segments into ad platforms for retargeting audiences. Klaviyo API Docs
• Strong behavioral segmentation: - abandoned carts
• viewed product but didn’t buy
• VIP customers
• churn-risk customers
• recent purchasers
• Supports coordinated email + ad sequences. Klaviyo documents syncing segments to Meta custom audiences and using those audiences for retargeting and lookalikes. Klaviyo Help Center

Example campaign:

1. Customer views a product
2. Send browse-abandon email after 4 hours
3. Show Meta/Google ads for 7 days
4. Suppress after purchase

Choose this if: your email data is your most valuable marketing asset.

3. Customer.io — best for product-led companies

customer.io

Best for: apps, SaaS, marketplaces.

Strengths:

• Event-driven campaigns based on product usage
• Flexible API/event pipelines
• Better fit when actions inside your product matter more than email lists

Example:

• User signs up
• Doesn’t complete onboarding
• Email reminder + retargeting audience + in-app message

4. AdRoll — best dedicated retargeting layer

adroll.com

Best for: teams that already have an ESP and want an advertising-focused platform.

Strengths:

• Built specifically around retargeting
• Cross-channel display/social capabilities
• Can complement email platforms rather than replace them

My shortlist by scenario

A good architecture is usually:

Customer data source (CRM/ESP) → audience sync layer → ad networks → conversion events back into customer profile

For most companies today:

• Ecommerce: Klaviyo + Meta Ads + Google Ads is the practical default.
• B2B: HubSpot + LinkedIn Ads + Google Ads is usually the cleaner setup.

If you share your email provider (e.g., Mailchimp, Braze, HubSpot, Klaviyo, Salesforce), industry, and ad channels (Meta/Google/LinkedIn/TikTok), I can narrow this to a specific recommendation.

For a combined email + paid retargeting campaign stack, I’d look at platforms that can sync your email/CRM audiences into ad networks (Meta, Google, LinkedIn, etc.), automate audience updates, and support suppression rules so email and ads don’t compete.

Here are strong options by use case:

My shortlist

• If you are ecommerce (Shopify/Klaviyo/Mailchimp): start with AdRoll. It is purpose-built for coordinated email + display/social retargeting. AdRoll Help Center
• If you are B2B (Salesforce/HubSpot + LinkedIn/Google): choose LeadsBridge or a CRM audience platform. LeadsBridge
• If you already have a mature marketing stack: use Zapier or a dedicated audience sync tool to avoid replacing your ESP/CDP. Zapier

Recommended campaign architecture

1. Email provider / CRM - Segments: leads, engaged subscribers, abandoned carts, customers, high-value accounts.
2. Audience sync layer - Automatically pushes segments to ad platforms.
3. Ad networks - Meta, Google Ads, LinkedIn, TikTok, display networks.
4. Suppression logic - Remove purchasers from acquisition ads.
5. Remove unsubscribed contacts from paid targeting where required.
6. Measurement - Compare email-only vs email + ads lift.

If you tell me your email provider (e.g., HubSpot, Klaviyo, Mailchimp, Marketo, Salesforce Marketing Cloud) and your main ad channels (Meta, Google, LinkedIn, TikTok, etc.), I can narrow this to the best 2–3 options.

If your goal is one retargeting strategy spanning email + paid media, my first recommendation is Klaviyo—assuming your email provider is already Klaviyo or you’re open to consolidating there.

Why Klaviyo is a strong fit

• Shared audiences: Build one segment—e.g. “viewed product, no purchase in 7 days”—and use it for both email and advertising. Klaviyo Help Center
• Multiple ad networks: Klaviyo supports audience syncing with Meta, Google Ads, TikTok, Pinterest, and Criteo. Klaviyo
• Retargeting + suppression: You can retarget cart abandoners, browsers, lapsed customers, etc., while excluding recent purchasers so you don't waste ad spend. Klaviyo Help Center Klaviyo
• Cross-channel journeys: A useful setup is email → ads → email, with the audience changing based on whether someone purchases or engages. Klaviyo specifically supports this type of journey-oriented advertising strategy. Klaviyo Dev Docs
• Lookalikes: Your high-value/VIP segments can become lookalike audiences on advertising platforms. Klaviyo Help Center

For example:

Viewed product → Email #1 → Meta/Google retargeting → Email #2 → Purchase → suppress from ads

That is considerably cleaner than having your email platform and ad platforms operate as disconnected campaigns.

One important caveat

If you already have an email provider, the recommendation depends heavily on which one. Klaviyo makes the most sense if you're using—or willing to migrate to—Klaviyo. If you're on HubSpot, Salesforce Marketing Cloud, Braze, Mailchimp, Iterable, Customer.io, etc., I'd evaluate a CDP/audience-sync layer instead of replacing your existing email system.

If you tell me your email provider + the ad networks you use (Meta, Google, TikTok, LinkedIn, etc.), I can recommend the best 2–3 solutions and compare them on integration depth, audience syncing, journey orchestration, attribution, and cost.

If your goal is one retargeting strategy that uses your email audience/behavioral data and activates it across paid networks, my first choice would be klaviyo.com—assuming your email provider is already Klaviyo.

Best fit: Klaviyo + Meta + Google

Klaviyo can use the same segments that drive your email campaigns as advertising audiences. Its current integrations support:

• Meta (Facebook/Instagram): sync Klaviyo lists/segments into Meta Custom Audiences. Klaviyo Help Center Klaviyo
• Google Ads: sync segments to Google Audiences for retargeting, targeting optimization, and suppression. Klaviyo Help Center
• TikTok and Pinterest: Klaviyo also supports audience activation on these networks. Klaviyo Academy Klaviyo Help Center
• Cross-channel suppression: for example, stop advertising to someone immediately after they purchase while continuing an email/post-purchase journey. Klaviyo Docs

That makes the architecture fairly clean:

Klaviyo segment → Email + Meta + Google → shared customer journey

For example, you could create a “Viewed product, no purchase in 7 days” segment and simultaneously:

1. Send an email.
2. Retarget the person on Meta.
3. Retarget them through Google.
4. Remove them from all retargeting as soon as they purchase.
5. Move purchasers into a cross-sell or loyalty audience.

Klaviyo specifically documents these kinds of cart-abandonment, winback, re-engagement, cross-sell, and cross-channel use cases. Klaviyo Help Center Klaviyo Help Center

When I'd choose something else

If you don't use Klaviyo, Customer.io is worth considering. Its integrations include Google Ads audience export specifically for lookalike and retargeting campaigns, plus Facebook Lead Ads. Customer.io

If what you really want is broad programmatic/display retargeting beyond Meta and Google, I'd evaluate AdRoll alongside your email platform rather than relying solely on native audience sync. That's a different strength: broader paid-media coverage versus tighter first-party email-data activation.

My recommendation: if you're already on Klaviyo, start with Klaviyo's native ad integrations rather than adding a separate retargeting vendor. It gives you the least fragmented setup and lets your email segmentation become the central audience layer.

If you tell me which email provider you use (Klaviyo, HubSpot, Mailchimp, Customer.io, Attentive, etc.) and which ad networks you run, I can narrow this down to the best 2–3 solutions and compare integration depth, audience syncing, attribution, and likely cost.

For a combined email + paid retargeting strategy, I’d look at platforms that can unify audience segments from your email provider/CRM with ad networks (Meta, Google, TikTok, LinkedIn, etc.) rather than running disconnected campaigns.

Here are strong options by use case:

1. Customer.io — best if your email provider is also your engagement hub

Best for: lifecycle marketing teams that want email, SMS, and ads driven from the same customer segments.

Why it fits:

• Syncs audience segments to ad networks such as Google Ads and Meta for retargeting/lookalike campaigns. Customer.io Customer.io
• Lets you build segments from behavioral events (cart abandonment, inactive users, high-value customers) and activate those audiences across channels. Customer.io
• Supports integrations with many marketing/data tools. Customer.io

Typical campaign:

• Email: “You left items in your cart”
• Ads: Show the same product reminder on Meta/Google
• Exclusion: Remove purchasers from acquisition ads

Good fit if you already use Customer.io or want a marketing automation platform.

2. Hightouch or Census — best if you have a warehouse/CDP

Best for: companies with customer data in Snowflake, BigQuery, Redshift, etc.

How it works:

• Your warehouse becomes the source of truth.
• Segments sync to: - Email platforms
• Meta Custom Audiences
• Google Customer Match
• Other ad destinations

Example segments:

• “Customers who bought twice but not in 90 days”
• “High-LTV users who opened emails but never converted”
• “Trial users who reached activation milestone”

This approach is usually the most flexible for larger teams.

3. Klaviyo — best for ecommerce brands

Best for: Shopify/DTC brands already using email flows.

Strengths:

• Strong customer segmentation.
• Good alignment between email journeys and paid audiences.
• Common workflows: - Browse abandonment email + Meta retargeting
• VIP customer email + lookalike audiences
• Win-back email + paid reactivation

4. Braze — best for enterprise cross-channel orchestration

Best for: apps, marketplaces, and large consumer businesses.

Useful when you need:

• Email + push + in-app + paid media coordination
• Complex customer journeys
• Real-time behavioral triggers

5. Opensend — best for visitor identification + retargeting

Best for: ecommerce teams trying to capture more anonymous website intent.

It focuses on identifying high-intent visitors and syncing audiences into email and advertising workflows. Opensend

My shortlist

A good architecture usually looks like:

Customer events → segmentation layer → email provider + ad networks → unified reporting

Before choosing, I’d check:

1. Which email provider are you using now (Klaviyo, HubSpot, Mailchimp, Salesforce Marketing Cloud, Braze, etc.)?
2. Which ad networks matter most (Meta, Google, TikTok, LinkedIn)?
3. Are you trying to retarget known customers only or also anonymous website visitors?

My shortlist

A good architecture usually looks like:

Customer events → segmentation layer → email provider + ad networks → unified reporting

Before choosing, I’d check:

If you want email + paid ads working as one retargeting system, I’d prioritize platforms that can sync your email/CRM segments into ad audiences automatically, rather than just cookie-based retargeting.

Here are strong options depending on your stack:

1. Customer.io — best if your email provider is your customer data hub

Good fit for: SaaS, apps, lifecycle marketing teams.

• Syncs audience segments from email/lifecycle campaigns into ad networks.
• Supports ad audience exports to platforms like Google Ads and Meta so the same segments used for email can drive paid campaigns. Customer.io Customer.io
• Useful campaign pattern: - Email: “trial users inactive 14 days”
• Ads: retarget those same users with a case study or reactivation offer
• Suppression: remove converted users from acquisition ads

Best when you already run segmentation in your messaging platform.

2. AdRoll — best all-in-one retargeting network

Good fit for: ecommerce, B2C, brands wanting display + social retargeting.

• Connects first-party email/CRM audiences and uses them for cross-channel campaigns.
• Supports integrations with tools such as Klaviyo, Mailchimp, Campaign Monitor, HubSpot, and others. AdRoll Help Center
• Useful for: - cart abandoners
• past purchasers
• lapsed customers
• email subscribers who never converted

3. LeadsBridge — best integration layer

Good fit for: companies with many systems.

• Acts as a connector between CRM/email tools and ad platforms.
• Can sync segmented lists into Meta Custom Audiences, Google Customer Match, LinkedIn Matched Audiences, etc. LeadsBridge
• Good if your email provider is not natively supported by your ad platform.

4. Zapier — best for lightweight workflows

Good fit for: smaller teams or custom automations.

Examples:

• New high-value customer in CRM → add to upsell ad audience
• Unengaged email subscriber → start win-back ads
• Customer converts → remove from prospecting campaigns

Zapier supports workflows connecting CRM, email, and ad platforms for audience updates. Zapier

My shortlist by scenario

A typical architecture I’d recommend:

Email provider / CRM
→ customer segments (trial, churn risk, VIP, abandoned cart)
→ audience sync layer
→ Google Ads + Meta + LinkedIn + other networks
→ coordinated email + ad journeys

A few questions would narrow this down:

1. Which email provider do you use (Klaviyo, HubSpot, Mailchimp, Salesforce Marketing Cloud, Customer.io, etc.)?
2. Which ad networks matter most (Meta, Google, LinkedIn, TikTok, Criteo)?
3. Is this mainly B2B lead nurturing or B2C/ecommerce retention?

A typical architecture I’d recommend:

If your goal is one retargeting layer that coordinates email audiences with multiple ad networks, my first recommendation would be AdRoll, particularly if your email provider is Klaviyo.

Best fit: AdRoll + Klaviyo

AdRoll integrates directly with Klaviyo, allowing Klaviyo lists and segments to flow into AdRoll. You can then use those audiences for retargeting across web, Meta, Instagram, Pinterest, TikTok, and CTV, with cross-channel reporting. Klaviyo Klaviyo

That enables campaigns such as:

• Cart abandoned: email → display/social retargeting → follow-up email.
• Browsed but didn't buy: email + ads with consistent product/message.
• Recent purchasers: suppress them from acquisition/retargeting campaigns.
• Winback: email inactive customers while simultaneously showing them ads.
• Cross-sell: email customers about complementary products and reinforce the offer with ads.
• VIP customers: create high-value audiences for special campaigns.

The particularly useful part is that your existing Klaviyo segmentation becomes the targeting logic, rather than maintaining separate audiences manually in each advertising platform. Klaviyo

If you already use Klaviyo

You may not actually need a third-party retargeting platform. Klaviyo itself can synchronize segments with Meta, Google, TikTok, Pinterest and other ad platforms, including custom/lookalike audiences. Klaviyo Academy Klaviyo Help Center

So I'd choose:

StackAdapt is another strong option if programmatic advertising is important: its Klaviyo integration imports customer profiles/events and supports personalized audiences across display, native, video and CTV. Klaviyo

If your email provider is not Klaviyo, tell me which one you use (e.g. HubSpot, Salesforce Marketing Cloud, Mailchimp, Braze, Iterable), and I can narrow this to the best 2–3 options for your stack.

If your goal is one retargeting strategy spanning email + paid media, I’d recommend Klaviyo as the orchestration layer.

klaviyo.com integrates directly with major ad networks including Meta, Google, TikTok, and Pinterest, allowing the same segments you use for email to become ad audiences. Klaviyo Academy Klaviyo Developers

Why it fits

• Unified audiences: Build segments such as cart abandoners, recent purchasers, lapsed customers, and high-value customers once, then use them for both email and ads.
• Cross-channel retargeting: Someone who receives an abandoned-cart email can simultaneously be targeted with a corresponding Meta or Google ad. Klaviyo specifically supports this type of cross-channel strategy. Klaviyo Help Center
• Suppression: Exclude purchasers, unsubscribers, or other audiences from paid campaigns so you're not wasting ad spend.
• Meta + Google: Klaviyo can sync segments to Meta Custom Audiences and Google Audiences. Google supports retargeting and exclusions based on Klaviyo profile data. Klaviyo Help Center Klaviyo Help Center
• Less manual work: Audience membership is synchronized rather than requiring repeated CSV exports/imports.

Recommended setup

Klaviyo → audience segments → Email + Meta + Google

For example:

One caveat: audience syncing isn't instantaneous. Meta says custom-audience updates can take 24–48 hours, while Google says processing can also take up to 48 hours. Klaviyo Help Center Klaviyo Help Center

Bottom line: If your email provider is already Klaviyo, I'd use its native advertising integrations rather than adding a separate retargeting vendor. If you're using Mailchimp, HubSpot, Customer.io, Braze, Iterable, etc., tell me which one and which ad networks you use, and I can recommend the best architecture/vendor for that exact stack.

If your goal is one retargeting layer that can coordinate email audiences with multiple ad networks, my first recommendation is AdRoll, especially if your email provider is Klaviyo.

Best fit: AdRoll + Klaviyo

AdRoll integrates with Klaviyo and lets you import Klaviyo lists/segments into AdRoll. You can then use those audiences for retargeting across web, CTV, and social, including Meta, TikTok, and Pinterest, while managing campaigns from AdRoll. Klaviyo

That makes it attractive for a combined journey such as:

• Email: cart-abandoner flow in Klaviyo
• Ads: same cart abandoners retargeted through AdRoll
• Suppression: purchasers removed from both campaigns
• Cross-channel: customers who don't engage with email continue seeing relevant ads
• Measurement: compare ROAS/CTR across the advertising campaigns in one place

adroll.com

If your email provider is Klaviyo

You may not actually need a separate retargeting platform. Klaviyo has native audience integrations with Meta, Google Ads, TikTok, Pinterest, and Criteo, allowing the same segments used for email to be pushed into advertising audiences. Klaviyo

For example, Klaviyo specifically supports using segments for cart abandoners, winbacks, cross-sells, re-engagement, and ad suppression in Google Ads. Klaviyo Help Center Meta audiences can likewise be built from Klaviyo lists and segments. Klaviyo Help Center

klaviyo.com

My shortlist

Criteo is particularly compelling if you have substantial ecommerce traffic and want dynamic product recommendations and broad web/social inventory. Criteo

Bottom line: if you're already on Klaviyo, I'd start with Klaviyo's native audience sync for simplicity and lower operational overhead. If you specifically want a dedicated retargeting platform that orchestrates campaigns across web + social + CTV, choose AdRoll.

If you tell me which email provider and ad networks you use, I can narrow this to the best 2–3 options and compare integrations, audience syncing, attribution, and likely implementation effort.

If your goal is one retargeting strategy that coordinates email with paid ads, I’d shortlist these:

1. klaviyo.com — best if your email platform is already Klaviyo.

Klaviyo can use the same behavioral/customer segments for email and advertising, syncing audiences to Meta, Google, TikTok, and Pinterest. That makes campaigns such as “cart abandoned → email + Meta/Google ads” relatively straightforward. Klaviyo Help Center Klaviyo Help Center Klaviyo Academy

2. adroll.com — best if you want a dedicated cross-channel retargeting layer.

Its Klaviyo integration imports lists and segments, then lets you run retargeting across web, CTV, and social, including Meta, TikTok, and Pinterest, from the AdRoll dashboard. Klaviyo

3. listrak.com — worth considering for larger/enterprise teams.

Listrak Exchange activates unified customer segments across paid channels such as Meta and Google, with use cases including cart-abandoner retargeting and suppression of existing customers. Listrak

My recommendation

If you already use Klaviyo: start with Klaviyo's native ad integrations before adding another retargeting vendor. It gives you a single segmentation layer for email + paid media and avoids unnecessarily duplicating customer data. For example:

• Browsed but didn't buy → email browse-abandonment flow + Meta/Google retargeting
• Added to cart → abandoned-cart email + higher-intent ads
• Purchased recently → suppress from acquisition/retargeting ads
• Lapsed customer → winback email + paid reactivation campaign
• VIP customers → exclude from discount campaigns or use them to build acquisition audiences

Klaviyo specifically supports using the same segments for cross-channel retargeting and exclusions. Klaviyo Help Center Klaviyo Help Center

If your email provider isn't Klaviyo, tell me which one you use (e.g. HubSpot, Salesforce Marketing Cloud, Braze, Mailchimp, Iterable), and I can narrow this to the best 2–3 options based on its integrations, ad networks, audience syncing, and pricing.

If your goal is one retargeting layer that coordinates email audiences with paid media, my first choice would be adroll.com.

Why it fits:

• Email → ads: AdRoll can sync audiences from Klaviyo, Mailchimp, ActiveCampaign, Constant Contact, Campaign Monitor, and others, so email segments can become retargeting audiences. AdRoll AdRoll
• Multiple ad networks: It connects with Meta/Instagram, Google Ads, TikTok, Pinterest, Amazon Ads, Snapchat, Microsoft Ads, LinkedIn and X, alongside display, native, video, mobile and CTV inventory. AdRoll AdRoll
• Audience suppression: You can use first-party data and purchase signals to avoid continuing to advertise to people who already converted—a particularly useful email + paid-media coordination use case. AdRoll AdRoll
• Cross-channel measurement: Its attribution/reporting layer can bring email and advertising performance together, rather than forcing you to compare disconnected dashboards. AdRoll
• API option: If your email provider isn't natively supported, AdRoll exposes APIs for audience creation, campaign management and reporting. AdRoll Developers

A strong alternative: Criteo

I'd choose criteo.com instead if you're primarily an ecommerce company with a large product catalog and want sophisticated dynamic-product retargeting. Criteo supports audience activation from platforms such as Klaviyo, Mailchimp, Bluecore and HubSpot, and combines that with dynamic retargeting across web and social. Criteo Criteo

One important caveat

If your email provider is Klaviyo, you may not actually need a separate retargeting platform for the basic use case. Klaviyo itself can sync segments directly to Meta and Google Ads, including using customer data for retargeting and exclusions. Klaviyo Help Center Klaviyo Help Center

So I'd rank the approaches:

1. AdRoll — best general-purpose choice for coordinated email + multi-network retargeting.
2. Criteo — best for sophisticated ecommerce/product retargeting at scale.
3. Klaviyo + native ad integrations — best if you're already heavily invested in Klaviyo and mainly need Meta/Google/TikTok activation rather than another advertising platform.

If you tell me which email provider and which ad networks you're using, I can narrow this to the best-fit architecture and flag exactly which integrations are native versus requiring a CDP/API.

If your goal is one retargeting layer that coordinates email audiences with paid media, my first choice would be Klaviyo—assuming your email provider is already Klaviyo.

Why it fits:

• Shared segmentation: the same customer segments used for email can be synced to advertising audiences. Klaviyo Help Center Klaviyo Help Center
• Major ad-network coverage: Klaviyo supports integrations with Meta, Google, TikTok, and Pinterest, allowing a segment to be activated across paid channels. Klaviyo Help Center
• Good retargeting workflows: you can target cart abandoners, lapsed customers, recent site visitors, or people who received an email but haven't converted. Klaviyo Help Center Klaviyo Help Center
• Suppression: you can exclude recent purchasers or other segments from acquisition campaigns, reducing wasted spend. Klaviyo Help Center
• Cross-channel messaging: Klaviyo explicitly supports using ads to reinforce an email campaign—for example, sending an abandoned-cart email while simultaneously retargeting the same audience on Meta. Klaviyo Help Center

If your email provider isn't Klaviyo

I'd consider HubSpot Marketing Hub if you want a broader CRM-centric solution. It can manage audiences and campaigns across Meta, Google, LinkedIn, and TikTok, while tying advertising activity to CRM contacts and revenue. HubSpot HubSpot Knowledge Base

The key distinction:

My recommendation: If you tell me which email provider you use (e.g., Salesforce Marketing Cloud, Braze, Mailchimp, Klaviyo, HubSpot) and which ad networks matter (Meta, Google, TikTok, LinkedIn, etc.), I can narrow this to 2–3 specific solutions and compare integration depth, audience syncing, attribution, and likely implementation effort.

If your goal is one retargeting strategy that coordinates email with paid media, I’d recommend Klaviyo—assuming your current email provider is Klaviyo.

Why it stands out:

• Shared audiences: Klaviyo segments can be synced directly to Meta and Google Ads, so the same customer segment used for email can drive your ad audiences. It also supports TikTok and Pinterest. Klaviyo Help Center Klaviyo Help Center
• Cross-channel campaigns: For example, you can target cart abandoners with an abandoned-cart email while simultaneously showing them ads with consistent messaging. Klaviyo specifically supports this type of cross-channel retargeting. Klaviyo Help Center Klaviyo Help Center
• Suppression: You can exclude recent purchasers or other segments from acquisition campaigns, reducing wasted ad spend. Klaviyo Help Center
• Lookalikes: Your high-value customer segments can be pushed to ad networks for lookalike/prospecting audiences. Klaviyo Academy
• Useful segmentation: Cart abandoners, lapsed customers, VIPs, recent purchasers, inactive subscribers, and cross-sell audiences can all become coordinated email + ad audiences. Klaviyo Academy Klaviyo Help Center

My shortlist

HubSpot is the stronger alternative if your email program is already built around a CRM/sales funnel: it connects Facebook, Google, LinkedIn and TikTok ad accounts and can send CRM lifecycle/conversion events back to ad networks. HubSpot Knowledge Base HubSpot Knowledge Base

If you tell me which email provider you currently use (Klaviyo, Mailchimp, HubSpot, Braze, Salesforce Marketing Cloud, etc.) and which ad networks you care about (Meta, Google, TikTok, LinkedIn, etc.), I can narrow this to the best 2–3 options and compare integration depth, cost, and setup effort.

For a combined email + paid retargeting campaign stack, I’d shortlist platforms that can take your email audience/behavior data and activate it across ad networks (Google, Meta, LinkedIn, programmatic, etc.). The best fit depends on whether you want a marketing automation hub, a dedicated retargeting layer, or a first-party audience sync tool.

Best overall options

1. AdRoll — best dedicated cross-channel retargeting platform

Best for: ecommerce, SMB/mid-market teams wanting email + display + social retargeting.

Why consider it:

• Syncs customer/email lists into advertising audiences.
• Runs display and social retargeting campaigns alongside email marketing.
• Good for abandoned cart, dormant customer, and lifecycle campaigns.
• Has integrations with common ecommerce and email platforms. Campaign Monitor

Typical setup:

• ESP segment: “opened email but didn’t purchase”
• Push segment → AdRoll audience
• Run ads for 7–30 days
• Suppress converters automatically

2. ActiveCampaign — best if email automation is the center

Best for: teams already using email journeys and wanting ad audiences connected to lifecycle stages.

Why consider it:

• Connects customer data across email, SMS, and advertising channels.
• Supports audience syncing with major ad platforms such as Facebook, Google Ads, TikTok, and LinkedIn. ActiveCampaign

Good use cases:

• Lead nurturing: - Email sequence → no response → add to paid audience
• Lead becomes sales-qualified → remove from acquisition ads
• Customer lifecycle: - Trial users → upgrade campaigns
• Churned users → win-back ads

3. Adobe Marketo Engage — best for enterprise B2B

Best for: large sales teams, ABM, long buying cycles.

Why consider it:

• Syncs marketing audiences into paid media systems.
• Supports integrations with major ad networks including Google, Facebook, and LinkedIn.
• Allows targeting based on engagement stage and buyer lifecycle. Experience League

Typical workflow:

• MQLs → LinkedIn + Google audiences
• Website visitors → nurture ads
• Closed customers → exclusion lists

4. Opensend — best for ecommerce visitor identification + retargeting

Best for: DTC brands trying to recover anonymous or high-intent visitors.

Why consider it:

• Connects with email marketing platforms.
• Supports retargeting through email, ads, and SMS.
• Designed around identifying and re-engaging high-intent shoppers. Opensend Opensend

5. illumin — best for programmatic + email audience activation

Best for: advertisers wanting to turn email segments into broader open-web campaigns.

Why consider it:

• Lets advertisers connect email audiences to programmatic campaigns.
• Supports behavioral audience segmentation and coordinated journeys. Illumin

My recommendation by scenario

A strong combined campaign architecture

1. Email provider creates behavioral segments:

• Opened but didn’t click
• Clicked but didn’t convert
• Viewed pricing/product pages
• Existing customers
• Lapsed customers
• Audience sync layer pushes segments to:

• Google Ads Customer Match
• Meta Custom Audiences
• LinkedIn Matched Audiences
• Display/programmatic networks
• Campaign logic:

• Email gets first touch
• Ads reinforce the message
• Purchasers are suppressed from acquisition campaigns
• High-value customers enter upsell flows

If you tell me your email provider (Klaviyo, HubSpot, Mailchimp, Salesforce Marketing Cloud, etc.), ad networks (Meta/Google/LinkedIn/programmatic), and whether this is B2B or ecommerce, I can narrow it to 2–3 platforms and a recommended stack.

If your goal is one retargeting strategy that coordinates email with paid media, my first choice would be Klaviyo—especially if your email provider is already Klaviyo.

Why it fits:

• Shared audiences: Klaviyo segments can be synced directly to Meta custom audiences and Google Ads audiences, so the same segments powering email can power retargeting. help.klaviyo.comhelp.klaviyo.com
• Cross-channel suppression: You can exclude recent purchasers or people already being reached through owned channels, reducing wasted ad spend. help.klaviyo.comintegrations.klaviyo.com
• Behavior-based retargeting: Build segments such as cart abandoners, recent browsers, lapsed customers, VIPs, or cross-sell candidates and use them in both email and ads. academy.klaviyo.com
• Multiple ad networks: Beyond Meta and Google, Klaviyo supports audience syncing with platforms including TikTok and Pinterest. academy.klaviyo.com
• First-party data: This avoids building your strategy around third-party cookies and lets your customer/behavior data drive targeting. help.klaviyo.comintegrations.klaviyo.com

A practical campaign structure

One caveat: audience synchronization isn't instantaneous. Klaviyo says new Meta and Google audiences can take up to roughly 24–48 hours to populate/process, so I wouldn't choose it if you need millisecond-level retargeting orchestration. help.klaviyo.comhelp.klaviyo.com

If you're not using Klaviyo for email, tell me which provider you use (e.g. HubSpot, Mailchimp, Braze, Iterable, Salesforce Marketing Cloud), plus which ad networks you need (Meta, Google, TikTok, LinkedIn, etc.). I can recommend the best-fit retargeting/CDP solution for that stack.

For a combined email + paid retargeting strategy, I’d look at platforms that can sync audience segments between your email/CRM system and ad networks (Meta, Google Ads, TikTok, LinkedIn, programmatic) rather than treating email and ads as separate channels.

Here are strong options depending on your stack:

My default recommendation

For most teams, I’d shortlist:

1. Customer.io — if you already have an ESP/CDP mindset and want flexible behavioral segments:
   • “Viewed product but didn’t buy” → email nurture + Meta retargeting
   • “Trial expired” → win-back email + Google audience
   • “Existing customers” → suppress from acquisition ads

docs.customer.io

2. Braze — if you need enterprise-scale orchestration, governance, and many channels. www.braze.com

3. Listrak — if your business is ecommerce-heavy and revenue attribution across email/SMS/ads is the priority. www.listrak.com

Architecture I’d aim for

Website / App Events
        ↓
Customer Data Platform or Marketing Automation
        ↓
Audience Segments
   ↙              ↘
Email Provider     Ad Networks
   ↓                 ↓
Email journeys     Retargeting / Lookalikes
        ↘         ↙
       Unified reporting

Key capabilities to verify before choosing:

• Native integrations with your email provider
• Audience sync with Google Ads Customer Match and Meta Custom Audiences
• Automatic suppression of converters (avoid wasting ad spend)
• Event-based triggers (cart abandonment, trial expiry, product interest)
• Consent/privacy controls and hashed audience transfers
• Conversion attribution across email + ads

If you tell me your current email provider (e.g., Klaviyo, HubSpot, Mailchimp, Salesforce Marketing Cloud, Braze, Customer.io, etc.), ad channels, and whether you’re B2B or ecommerce, I can narrow this to 2–3 best fits.

If your goal is one retargeting strategy spanning email + paid ads, my first choice would be Klaviyo—especially if you're ecommerce/DTC.

Why Klaviyo is a strong fit

• Email + audience data in one place: Build segments from purchase history, browsing, cart activity, email engagement, etc., then use those same segments for paid retargeting.
• Major ad-network integrations: Klaviyo supports audience syncing with Google Ads, Meta, TikTok, and Pinterest, allowing the same first-party segments to power multiple channels. academy.klaviyo.com
• Cross-channel campaigns: For example, someone who abandons a cart could enter an email flow while simultaneously being added to a Meta/Google retargeting audience. help.klaviyo.comhelp.klaviyo.com
• Exclusions: You can suppress recent purchasers or people already responding to your email campaigns from paid audiences, reducing wasted spend. www.klaviyo.com
• Lookalikes: High-value customer segments can also be pushed into ad platforms to find similar prospects. help.klaviyo.comhelp.klaviyo.com

One caveat: audience syncing isn't necessarily instantaneous. For example, Klaviyo says Meta custom audiences can take 24–48 hours to update, and Google can take up to 48 hours to process new audiences. help.klaviyo.comhelp.klaviyo.com

When I'd choose something else

If your email/CRM provider is already HubSpot, I'd strongly consider staying in that ecosystem instead. HubSpot can create audiences from website visitors and contacts and synchronize them with Facebook/Meta, Google, and LinkedIn; its audience synchronization is bidirectional. knowledge.hubspot.com

My shortlist:

If you tell me which email provider you use (e.g. Mailchimp, Salesforce Marketing Cloud, Klaviyo, HubSpot, Braze) and which ad networks matter (Meta, Google, LinkedIn, TikTok, etc.), I can narrow this to the best 2–3 options and compare integration depth, audience syncing, campaign orchestration, and cost.

If your goal is one retargeting strategy that connects email behavior with multiple ad networks, my first choice would be Klaviyo—assuming your email provider is already Klaviyo or you’re willing to consolidate there.

Best fit: Klaviyo + Meta + Google Ads

Klaviyo can use the same first-party segments that drive your email campaigns and sync them to Meta, Google Ads, TikTok, and Pinterest for custom/lookalike audiences. academy.klaviyo.com

That enables campaigns such as:

• Cart abandoner: email + Meta/Google retargeting, with purchasers automatically excluded.
• Product viewer: email follow-up + ads featuring the product they viewed.
• Winback: reactivation email plus paid ads for customers who haven't purchased recently.
• Cross-sell: email customers who bought Product A while advertising complementary Product B.
• Suppression: exclude recent purchasers or people already engaging heavily with email so you don't pay to reach them unnecessarily. help.klaviyo.com

Klaviyo's Google integration specifically supports syncing segments to Google Audiences and using purchase/behavioral data for retargeting and exclusions. help.klaviyo.com Meta supports the equivalent custom-audience workflow, although Meta's audience updates can take 24–48 hours. help.klaviyo.com

Klaviyo advertising integrations

Strong alternative: HubSpot

If your email provider is HubSpot, I wouldn't add another retargeting platform. HubSpot's ads product manages campaigns across Meta, Google, LinkedIn, and TikTok, and its audiences can be based on contacts and website visitors. www.hubspot.com

It's particularly attractive if you want CRM lifecycle stages + email + paid advertising + revenue attribution in one system. HubSpot's Meta integration can also send conversion events back to Meta based on outcomes such as lifecycle-stage changes and closed deals. ecosystem.hubspot.com

HubSpot Ads

My recommendation:

• E-commerce / DTC: Klaviyo is the better fit.
• B2B / sales-led: HubSpot is probably better.
• Already happy with another email provider: tell me which one (e.g. Mailchimp, Salesforce Marketing Cloud, Braze, Iterable, ActiveCampaign), and I can recommend the best retargeting layer that integrates with it and compare pricing, supported ad networks, audience sync, attribution, and setup complexity.

If your goal is one retargeting strategy that coordinates email with paid ads, my first choice would be Klaviyo—assuming your email provider is already Klaviyo, or you're open to consolidating there.

Why Klaviyo is a strong fit

• One audience layer: Build segments from email engagement, browsing behavior, purchases, cart activity, and customer lifecycle data, then use those same segments for advertising. help.klaviyo.comwww.klaviyo.com
• Meta + Google: Klaviyo can sync segments into Meta Custom Audiences and Google Audiences, enabling retargeting and lookalike campaigns. help.klaviyo.comhelp.klaviyo.com
• More networks: Klaviyo also documents integrations with TikTok and Pinterest, so you're not locked into just Meta/Google. academy.klaviyo.com
• Cross-channel exclusions: You can, for example, stop advertising to recent purchasers while they receive a post-purchase email sequence, or coordinate an abandoned-cart email with matching ads. help.klaviyo.comhelp.klaviyo.com
• First-party data: This is particularly useful as third-party-cookie targeting becomes less dependable. Your CRM/email data becomes the audience source rather than relying exclusively on ad-network pixels. help.klaviyo.comwww.klaviyo.com

Klaviyo official site

Example campaign architecture

One caveat: this isn't necessarily a single unified ad-buying interface. Klaviyo primarily acts as the customer-data/audience orchestration layer, while Meta, Google, etc. remain the places where the ads are actually managed. Audience syncing can also have processing delays—for example, Klaviyo says Meta custom audiences may take 24–48 hours to update. help.klaviyo.comhelp.klaviyo.com

If you tell me which email provider you currently use (e.g. HubSpot, Mailchimp, Salesforce Marketing Cloud, Braze, Customer.io) and which ad networks matter (Meta, Google, TikTok, LinkedIn, etc.), I can recommend the best 2–3 solutions for your specific stack.

If your goal is one audience strategy spanning email + retargeting ads, my first choice would be Klaviyo—especially if your email provider is already Klaviyo.

Best fit: Klaviyo

Klaviyo lets you build a segment once—e.g. cart abandoners, recent purchasers, lapsed customers, VIPs—and use that same segment for email/SMS and paid audiences. Its current ad integrations support Google Ads, Meta, TikTok, and Pinterest. help.klaviyo.com

For example:

Cart abandoned →

• Send abandoned-cart email
• Simultaneously retarget on Meta/Instagram
• Retarget through Google
• Suppress anyone who purchases from subsequent ads
• Use the same customer segment for measurement/optimization

Klaviyo specifically supports syncing segments to Google audiences for retargeting and exclusions, while its Meta integration supports custom audiences and lookalikes. help.klaviyo.com

One caveat: audience syncing isn't necessarily instantaneous—Klaviyo says Meta custom-audience updates can take 24–48 hours. help.klaviyo.com

Klaviyo

Strong alternative: HubSpot

If you're more B2B/CRM-driven than ecommerce-driven, I'd look at HubSpot. It connects CRM audiences to Meta, Google, LinkedIn, and TikTok, and can send lifecycle-stage/conversion information back to ad platforms. knowledge.hubspot.com

HubSpot Marketing & Ads

My recommendation:

• Ecommerce / DTC: Klaviyo
• B2B / sales-led: HubSpot
• Already using another email provider: tell me which one (e.g. Mailchimp, Braze, Salesforce Marketing Cloud, Iterable, Customer.io), plus which ad networks you use, and I can narrow it to the best integration architecture.

If your goal is one retargeting setup that coordinates email with paid ads, I’d shortlist these:

My pick: Klaviyo

If you're already using Klaviyo for email, I would use it as the customer/audience layer rather than adding a separate retargeting platform. Klaviyo can sync segments into Meta and Google Ads, allowing the same audience logic to power email and paid campaigns. It also supports TikTok and Pinterest integrations. help.klaviyo.com

For example:

Segment: Viewed product → didn't purchase
→ Email reminder
→ Meta/Instagram retargeting
→ Google remarketing
→ Remove from both once purchase occurs

That gives you coordinated sequencing instead of independently targeting the same customer through every channel.

If you're not on Klaviyo

I'd lean toward Customer.io for a SaaS/product business. Its audience-sync functionality can automatically push behavioral segments to Google and Meta, while those same segments can power email and other messaging. Customer.io says its ad-audience sync runs automatically rather than requiring CSV uploads. customer.io

Bottom line:

• Ecommerce: Klaviyo
• SaaS / behavioral lifecycle: Customer.io
• Large-scale, product-heavy ecommerce retargeting: Criteo www.criteo.com

If you tell me which email provider and which ad networks you currently use (e.g. HubSpot + Google/Meta, Salesforce + LinkedIn, Klaviyo + Meta/Google), I can recommend the best architecture and 2–3 alternatives.

If your goal is one retargeting strategy spanning email + paid ads, my first recommendation is Klaviyo—assuming your email provider is already Klaviyo or you’re open to consolidating there.

Best fit: Klaviyo + native ad integrations

Klaviyo can use the same customer segments for email and paid retargeting, then sync those audiences into Meta, Google Ads, TikTok, Pinterest, and Criteo. www.klaviyo.com

That enables campaigns such as:

• Cart abandoner: email reminder + Meta/Google ads for people who haven't purchased.
• Winback: email offer + ads to lapsed customers.
• Cross-sell: post-purchase email + ads for complementary products.
• Suppression: stop showing ads to people who just purchased or are already converting.
• Lookalikes: build paid acquisition audiences from your highest-value email/customer segments.

Klaviyo specifically supports syncing lists/segments to Meta custom audiences and Google audiences. help.klaviyo.com

One caveat: Meta audience updates can take 24–48 hours, so it isn't truly instantaneous retargeting on that network. help.klaviyo.com

If you already use another email platform

Customer.io is a strong alternative if you're more of a SaaS/product-led business. It can programmatically export Customer.io segments to ad networks for retargeting and lookalike campaigns, including Google and Facebook/Instagram, while keeping audience definitions aligned between messaging and advertising. docs.customer.io

Salesforce Data 360 + Digital Advertising is the heavier enterprise option if you need a broader customer-data layer. It can activate first-party audiences across Meta, Google, Amazon Ads, The Trade Desk, CTV partners and others, with centralized cross-channel measurement. www.salesforce.com

My recommendation

If you tell me which email provider you're using and which ad networks (Meta, Google, TikTok, LinkedIn, etc.), I can narrow this down to the best 2–3 options and compare their integration depth, audience syncing, attribution, pricing, and setup effort.

If your goal is one retargeting system that coordinates email audiences with multiple ad networks, my first choice would be Klaviyo—especially if your email provider is already Klaviyo.

Best fit: Klaviyo + ad-network integrations

Klaviyo can take the same first-party segments you use for email and sync them into advertising platforms. Its current integrations include Meta, Google Ads, TikTok, and Pinterest. help.klaviyo.com

That enables campaigns such as:

The particularly useful part is audience synchronization: Klaviyo segments can be connected to Google Audiences and Meta Custom Audiences rather than manually exporting/importing lists. help.klaviyo.comhelp.klaviyo.com

For example, you could create a Checkout started AND no purchase in 7 days segment, send an abandoned-cart email, and simultaneously put those people into Meta/Google retargeting audiences with matching creative. Klaviyo specifically documents this cross-channel use case. help.klaviyo.com

One caveat: this is primarily an audience orchestration/data-sync solution, not a single interface that completely replaces every ad network's campaign-management interface. Meta audience updates can also take 24–48 hours. help.klaviyo.comhelp.klaviyo.com

If your email provider isn't Klaviyo

I'd evaluate HubSpot if you want a broader CRM/marketing platform, particularly when you need unified lead/customer lifecycle data and ad reporting. Its Meta integration supports audience building, lead syncing, conversion events, and reporting alongside other ad networks. ecosystem.hubspot.com

For a business heavily focused on commerce-oriented dynamic retargeting across the open web, I'd also consider Criteo. It specializes in dynamic product retargeting and cross-channel inventory, but it's less of a replacement for your email/CRM platform. www.criteo.com

My recommendation:
Klaviyo → audience/CRM source → Meta + Google + TikTok/Pinterest, with email and ads using the same lifecycle segments. That's the cleanest architecture if your priority is combined campaigns rather than simply buying retargeting inventory.

If you tell me which email provider you use (Klaviyo, Mailchimp, HubSpot, Salesforce Marketing Cloud, Braze, etc.) and which ad networks matter most, I can narrow this to 2–3 specific solutions and compare integration depth, audience syncing, attribution, and likely implementation effort.

If your goal is one retargeting layer that coordinates email audiences with paid ads, I’d shortlist these:

1. Klaviyo — best overall for ecommerce/B2C
   • Uses your email/customer data to build behavioral segments such as cart abandoners, browsers, lapsed customers, and VIPs.
   • Syncs those segments directly to Meta, Google Ads, TikTok, Pinterest, etc. www.klaviyo.com
   • Supports suppression audiences, so someone who just purchased can automatically stop receiving acquisition/retargeting ads. integrations.klaviyo.com
   • Particularly good for coordinated journeys like email → wait → retargeting ad → purchase → suppress from ads. www.klaviyo.comdevelopers.klaviyo.comintegrations.klaviyo.comcustomer.io

2. AdRoll — best if you want the ad platform itself to orchestrate the campaigns
   • Has a direct Klaviyo integration that syncs lists/segments into AdRoll.
   • Combines web/display, Facebook, Instagram, Pinterest, and email campaigns and provides cross-channel reporting. integrations.klaviyo.com
   • A strong choice if your priority is one interface for running and measuring paid retargeting across networks.

3. Customer.io — best for sophisticated lifecycle/product-led journeys
   • Syncs behavioral segments to Meta and Google Ads, including retargeting and lookalike audiences.
   • Its audience automation can refresh ad audiences hourly, which is useful for rapidly changing lifecycle segments. customer.io

My recommendation

Choose Klaviyo if your email provider is already Klaviyo. It gives you the cleanest first-party-data setup: segment once, then activate the same audience in email and multiple ad networks. Its current integrations with Google and Meta are particularly mature. www.klaviyo.com

Choose AdRoll if you specifically want a dedicated cross-channel advertising/retargeting platform sitting alongside your email provider.

If you tell me which email provider you use (e.g., HubSpot, Mailchimp, Klaviyo, Salesforce Marketing Cloud) and which ad networks you need (Meta, Google, TikTok, LinkedIn, etc.), I can narrow this to the best 2–3 options and compare integration depth, audience syncing, journey orchestration, attribution, and approximate cost.

If your goal is one audience strategy spanning email + paid retargeting, my first choice would be Klaviyo + AdRoll.

• Klaviyo as the customer/audience layer: build segments from email engagement, browsing, cart activity, purchase history, and lifecycle stage.
• AdRoll as the cross-channel retargeting layer: its Klaviyo integration can import lists/segments and use them for campaigns across web, CTV, Meta, TikTok, and Pinterest, with campaign performance/ROAS in the AdRoll dashboard. marketplace.klaviyo.com
• Alternatively, Klaviyo can connect directly to Meta, Google Ads, TikTok, Pinterest and Criteo, so you don't necessarily need a separate retargeting platform. www.klaviyo.comacademy.klaviyo.com

Which I'd pick

Klaviyo's direct integrations are particularly strong for combined email/ad journeys. For example, you can create a "started checkout but didn't purchase" segment and use essentially the same audience logic for an abandoned-cart email and Google/Meta retargeting. Google audience sync can also be used to exclude recent purchasers from advertising. help.klaviyo.com

If you already use Klaviyo for email, I'd therefore start with Klaviyo + direct Meta/Google integrations, adding AdRoll only if you specifically want centralized web/CTV/social retargeting. Klaviyo says its audience-sync integrations also cover TikTok, Pinterest and Criteo. www.klaviyo.comacademy.klaviyo.com

If you tell me which email provider you use and which ad networks (Meta, Google, LinkedIn, TikTok, etc.), I can narrow this to the best 2–3 solutions and compare integration depth, audience syncing, attribution, and likely cost.

If your goal is one audience/segmentation layer powering both email and paid retargeting, I’d shortlist these:

My recommendation

If you're already using Klaviyo, stick with Klaviyo's native audience-sync capabilities rather than adding a separate retargeting platform. It supports Meta, Google Ads, TikTok, Pinterest and Criteo, so you can create segments such as:

• Viewed product, didn't purchase → email + Meta/Google retargeting
• Cart abandoned → abandoned-cart email + coordinated ads
• Recent purchasers → suppress from acquisition/retargeting
• High-value customers → cross-sell email + paid campaigns
• Lapsed customers → win-back email + retargeting
• Best customers → lookalike audiences

Klaviyo specifically supports syncing the same segments used for email to Google Ads, including retargeting and ad exclusions. help.klaviyo.comhelp.klaviyo.com Its Meta integration similarly supports custom-audience syncing and lookalikes. help.klaviyo.com

One caveat: audience syncing isn't necessarily instantaneous. Klaviyo notes that Meta and Google can take up to roughly 24–48 hours to process newly synced audiences, so I wouldn't choose a platform based on the expectation of second-by-second retargeting. help.klaviyo.comhelp.klaviyo.com

If you tell me which email provider you use (Klaviyo, HubSpot, Mailchimp, Customer.io, Braze, etc.) and which ad networks you need (Meta, Google, TikTok, LinkedIn, etc.), I can narrow this to the best 2–3 options and compare integration depth, audience sync, attribution, and likely implementation effort.

If your goal is one retargeting strategy that coordinates email with paid media, I’d shortlist these:

1. Klaviyo — best if email is the center of your stack

Klaviyo is particularly attractive if your email provider is already Klaviyo. It can sync customer lists/segments into Google Ads and Meta Ads, letting you use the same behavioral segments for email and advertising—for example, “cart abandoners,” “bought in the last 30 days,” or “lapsed customers.” help.klaviyo.com

Example combined campaign

• Email: cart-abandonment sequence
• Meta/Google: retarget non-purchasers
• Suppression: remove purchasers from both
• Follow-up: shift recent purchasers into cross-sell messaging

Why I'd choose it: relatively simple, strong first-party customer segmentation, and good orchestration if email is already your primary customer-data system.

2. Criteo Commerce Growth — best for serious cross-channel retargeting

Criteo is stronger if you want a dedicated advertising/retargeting engine alongside your email platform. Its Commerce Growth platform supports personalized retargeting across web, mobile, social, video and other inventory, and can ingest first-party data through CDP/CRM connections or contact lists. www.criteo.com

This is the option I'd investigate for a larger ecommerce operation where dynamic product ads, broad publisher reach, and automated bidding/optimization matter more than keeping everything inside the email platform.

My recommendation

One important distinction: Klaviyo coordinates audiences between email and ad networks; Criteo is more of a dedicated media/retargeting platform. So if by “combined campaigns” you mean the same customer segment should automatically receive coordinated email + Meta/Google ads, I'd start with Klaviyo. Its integrations can sync segments to advertising audiences and use purchase behavior for targeting/exclusion. help.klaviyo.com

If you tell me which email provider and which ad networks you use (e.g. HubSpot/Mailchimp/Klaviyo + Meta/Google/LinkedIn/TikTok), I can recommend the best-fit architecture and compare the integration options.

If your goal is one retargeting layer that coordinates email audiences with paid media, I’d shortlist these:

1. Klaviyo — best if your email provider is already Klaviyo

This is my first choice for ecommerce/consumer brands. Klaviyo can turn email/customer segments—such as cart abandoners, recent browsers, lapsed customers, and purchasers—into advertising audiences and sync them with Meta, Google Ads, TikTok, Pinterest, and Criteo. www.klaviyo.com

The useful part is the cross-channel segmentation: for example, someone can receive an abandoned-cart email while simultaneously being targeted with a coordinated Meta/Google campaign, while recent purchasers can be excluded from acquisition ads. help.klaviyo.com

Klaviyo

2. HubSpot — best if you want CRM + advertising orchestration

HubSpot is stronger if your email marketing is part of a broader CRM/lifecycle-marketing stack. Its audiences can be built from contacts and website visitors and synchronized with Facebook/Instagram, Google, and LinkedIn. Audience synchronization is bidirectional, and workflows can automate audience membership. www.klaviyo.comknowledge.hubspot.comecosystem.hubspot.com

It also gives you more unified campaign reporting and can feed lifecycle/conversion information back into Meta for optimization. ecosystem.hubspot.com

HubSpot Marketing Hub

My recommendation

One important caveat: these platforms generally aren't replacing Meta/Google's ad buying engines. They act as the customer-data/audience orchestration layer, keeping your paid audiences aligned with email and behavioral segments.

If you tell me which email provider you use (e.g. Mailchimp, Salesforce Marketing Cloud, Braze, Iterable, Klaviyo) and which ad networks you need (Meta, Google, TikTok, LinkedIn, etc.), I can narrow this to the best 2–3 options and compare integration depth, audience syncing, attribution, and likely cost.