Third-party cookies are small tracking files placed on your browser by a domain you didn’t visit directly usually an ad network or analytics platform. They power cross-site behavioural tracking, retargeting, and audience segmentation. With major browsers phasing them out, the tools built on top of them are quietly breaking.
TL;DR
- Third-party cookies are set by external domains to track user behaviour across multiple websites, not just the one you’re visiting.
- Browsers like Safari and Firefox already block them by default, and Chrome has been moving toward the same restriction for years.
- Most SaaS retargeting campaigns depend on third-party cookies without the marketing team realising it until attribution starts breaking.
- First-party data strategies collecting data directly from your own users are the most durable replacement for third-party tracking.
- The deprecation of third-party cookies doesn’t kill digital advertising, but it does force a more honest relationship between brands and their audiences.
What Are Third-Party Cookies?
Third-party cookies are tracking files created by a domain other than the one the user is actively visiting. You land on a SaaS pricing page, but an ad network drops a cookie from its own domain in your browser that’s a third-party cookie doing its job.
Here’s how the mechanics work: when a page loads, it often pulls in scripts from external services ad platforms, analytics tools, customer data platforms, live chat widgets. Each of those services can set their own cookies. Because those cookies belong to external domains, they can track you across any site that loads the same scripts.
That’s the part most guides skim over. Third-party cookies aren’t just about ads. They’re the invisible infrastructure behind retargeting, cross-site analytics, A/B testing platforms, and attribution models. When they go away, it’s not just your Facebook pixel that breaks it’s your entire view of how users move through the web before they reach you.
- Cross-site tracking: A single third-party cookie can follow a user across thousands of websites, building a behavioural profile without that user ever interacting with the tracking company directly.
- Retargeting audiences: Ad platforms use these cookies to identify users who visited your site and serve them ads elsewhere the mechanism behind “why is this product following me around the internet.”
- Attribution modelling: Many multi-touch attribution tools rely on third-party cookies to stitch together a user’s journey across different sites and sessions.
- Audience segmentation: Data brokers and demand-side platforms use third-party cookie pools to build and sell audience segments based on inferred interests and behaviours.
- Third-party analytics: Some analytics tools not just ad platforms drop their own cookies, which means even your reporting stack may be affected.
Consider a B2B SaaS tool for legal teams. They run retargeting ads on Linked In and Google. Their attribution tool shows a clean path from ad click to demo. But when Safari users who have had third-party cookies blocked for years start converting, that attribution tool records them as direct traffic. The data looks fine. The picture is wrong.
The contrarian read here: most SaaS marketers treat cookie deprecation as a future problem. It’s not. Safari blocked third-party cookies in 2017. Firefox followed. A meaningful chunk of your audience has been invisible to your retargeting stack for years you just didn’t know it because your reporting never flagged it.
Also read: how top B2B PPC agencies are adapting paid strategies to cookieless targeting
Why Are Third-Party Cookies Being Phased Out?
The short answer: browsers decided that cross-site tracking without user consent was a privacy problem worth fixing. The longer answer involves regulatory pressure, competitive positioning, and a genuine shift in how users feel about being tracked.
GDPR in Europe, CCPA in California, and similar laws elsewhere have forced the issue into the open. Users now have to be told they’re being tracked and in many jurisdictions, they have to actively consent. Third-party cookies were never designed with that consent model in mind.
Fast Fact: Safari’s Intelligent Tracking Prevention, launched in 2017, was the first major browser move against third-party cookies most SaaS teams didn’t adjust their tracking assumptions until Chrome announced its own deprecation timeline years later.
- Browser competition: Apple and Mozilla positioned privacy as a feature. Blocking third-party cookies by default became a selling point, not just a policy decision.
- Regulatory pressure: GDPR and CCPA made it harder to justify cross-site tracking without explicit consent, pushing browsers and platforms to act before regulators forced their hand.
- User sentiment: Targeted ads that feel surveillance-like erode trust. Platforms that host those ads started feeling that reputational cost.
- Google’s position: Chrome’s deprecation has been slower because Google’s ad business depends on behavioural targeting they’ve been building alternatives (like the Privacy Sandbox) to replace the function without fully abandoning the revenue model.
The real trade-off here: blocking third-party cookies protects user privacy, but it also breaks attribution models that marketers have built entire budgets around. That’s not a small disruption it means teams need to rebuild how they measure campaign performance from the ground up, not just swap one tool for another.
What’s the Difference Between First-Party and Third-Party Cookies?
First-party cookies are set by the website you’re actually visiting. Third-party cookies are set by someone else’s domain, loaded through scripts on that page. That’s the core distinction and it matters a lot for what survives the current privacy shift.
First-Party Cookies
First-party cookies are created and controlled by the site owner. They store things like login sessions, shopping cart contents, language preferences, and user settings. A SaaS app that remembers you’re logged in between sessions is using a first-party cookie.
These aren’t going anywhere. Browsers have no interest in breaking the basic functionality of websites. First-party cookies are considered relatively safe from a privacy standpoint because they only work on the domain that set them they can’t follow you to another site.
Third-Party Cookies
Third-party cookies are set by an external domain typically an ad network, analytics provider, or tracking pixel. They work across sites because the same external script gets loaded on thousands of different pages. That’s what makes them useful for retargeting, and exactly what makes them a privacy concern.
The nuanced warning: some tools that marketers think of as “first-party” actually rely on third-party cookies under the hood. If your analytics platform or CRM uses an external tracking domain even if it’s whitelabelled it may still be setting third-party cookies. Check your cookie audit before assuming you’re covered.
| Type | Set by | Works across sites | Survives deprecation |
|——|——–|——————–|———————-|
| First-party | Site you’re visiting | No | Yes |
| Third-party | External domain | Yes | No (phasing out) |
| Session cookies | Either | No | Yes (browser session only) |
Also read: best B2B Google Ads agencies navigating first-party data transitions
How Does Third-Party Cookie Deprecation Affect SaaS Marketing?
It breaks the three things SaaS marketers rely on most: retargeting, attribution, and audience building. Each one needs a different fix.
Retargeting is the most visible casualty. If your ads are set up to re-engage users who visited your pricing page, that audience list shrinks every time a browser blocks the cookie that would have identified them. Safari and Firefox users have been invisible to most retargeting campaigns for years.
Fast Fact: Most SaaS attribution models were built assuming third-party cookies work across all browsers which means they’ve been undercounting conversions from Safari and Firefox users since at least 2020.
Attribution is the quieter problem. Without cross-site cookies, it’s harder to connect an ad impression on one platform to a conversion on your site. Models that used to stitch together a five-touch journey now have gaps. You’re not losing conversions you’re losing visibility into where they came from.
Audience building is the longest-term shift. Third-party data brokers built their segments on cookie pools. Those segments are degrading. The SaaS teams that will perform best in a cookieless environment are the ones building their own first-party data assets email lists, product usage signals, CRM enrichment before they need them.
- Retargeting audiences: Shrink as more browsers block third-party cookies, reducing reach on platforms like Google Display and Meta without a first-party data alternative.
- Multi-touch attribution: Breaks down when cross-site cookie chains can’t be completed, pushing teams toward probabilistic models or server-side tracking.
- Lookalike audiences: Become less accurate as the underlying cookie-based signals degrade especially on platforms that relied heavily on third-party data to build them.
- Frequency capping: Harder to enforce without a persistent cross-site identifier, which means users may see the same ad repeatedly without the platform knowing.
The teams that treat this as a tracking problem are going to keep chasing workarounds. The teams that treat it as a data strategy problem are going to build something more durable. Those are two very different responses to the same signal.
What Should SaaS Teams Do Instead of Relying on Third-Party Cookies?
Move to first-party data, server-side tracking, and contextual targeting in that priority order. None of these are perfect replacements, but together they cover most of what third-party cookies were doing.
First-Party Data Collection
This is the most durable shift. Collect data directly from your users through sign-ups, product usage, surveys, and CRM enrichment. A SaaS tool for project managers that knows which features each user engages with, what their team size is, and when they’re most active has more useful signal than any third-party cookie profile.
The catch: first-party data takes time to build. Teams that haven’t started yet are behind. If you’re running paid campaigns and still relying entirely on pixel-based retargeting, working with a specialist SaaS PPC agency that understands cookieless audience strategy is a faster path than rebuilding your data infrastructure alone.
Server-Side Tracking
Server-side tracking moves the data collection off the browser and onto your server. Instead of a browser cookie setting the signal, your server sends the event data directly to the ad platform or analytics tool. It’s more reliable, less affected by browser restrictions, and harder for ad blockers to interfere with.
The trade-off: server-side tracking is more complex to implement. It requires developer involvement, and you’re taking on more responsibility for data handling and compliance. It’s worth it for high-traffic SaaS products where attribution accuracy directly affects budget decisions less critical for early-stage teams still finding product-market fit.
Contextual Targeting
Contextual targeting places ads based on the content of the page not the behaviour of the user. No cookies needed. An ad for a SaaS security tool appearing on a cybersecurity blog is contextual targeting. It’s less precise than behavioural targeting, but it’s privacy-safe and doesn’t depend on any cross-site tracking infrastructure.
For best B2B marketing agencies helping clients through this transition, contextual has become a first-line strategy again something that was largely abandoned during the behavioural targeting era.
The Bottom Line
Third-party cookies are a fading technology, not a future problem. The SaaS teams that treat this as a compliance checkbox are going to find their retargeting, attribution, and audience tools quietly degrading over the next few years. The ones building first-party data infrastructure now and rethinking how they measure campaign performance will be in a much stronger position when the last browser flips the switch.
If you want to talk through how this affects your paid and organic strategy, get in touch with our team or see how our SaaS PPC service approaches cookieless campaign measurement in practice.
