ChatGPT answers, unedited

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.