In this guide
- A third-party cookie belongs to a different domain from the page you are on, such as an ad network's domain on a shop page.
- Safari and Firefox block them by default. Chrome kept them available and relied on user choice instead of removing them for everyone.
- The replacement is first-party data, server-side events and modelling.
Third-party cookies were the glue of the old ad web: one cookie that followed a person from site to site, so a network could show them a relevant ad or measure a conversion. Browsers and privacy rules have been taking it apart for years. This page explains what they are, where things stand and what to use instead. For the broader picture read cookieless tracking and tracking cookies.
How a third-party cookie works
You visit a shop
The page includes a script from an ad network.
The network sets a cookie
The cookie belongs to the network's domain, not the shop's.
You visit a news site that uses the same network
The network reads its cookie again.
It recognises you
It can show an ad for the shop or count that you saw one.
3 things to remember
Scroll and the points stack up.
A third-party cookie belongs to a different domain from the page you are on, such as an ad network's domain on a shop page.
Safari and Firefox block them by default. Chrome kept them available and relied on user choice instead of removing them for everyo
The replacement is first-party data, server-side events and modelling.
Where browsers stand
| Browser | Third-party cookies |
|---|---|
| Safari | Blocked by default for years through Intelligent Tracking Prevention |
| Firefox | Blocked by default through Enhanced Tracking Protection |
| Chrome | Still available. Google planned to remove them, then chose to keep them and use existing user controls |
| Edge, Brave and others | Vary. Brave blocks them by default. |
Google's plans for Chrome changed several times between 2020 and 2025. Check Chrome's current documentation for the latest position. Even where cookies remain available, ad blockers, privacy settings and consent banners mean a growing share of visitors cannot be followed with them.
What stops working without them
- Cross-site retargeting built on a network cookie.
- Frequency capping across publishers.
- Last-click attribution that depends on a cookie set on the ad domain.
- Cross-site audience syncing.
Runs on your domain, anywhere
Your tracking runs on your own domain, so a visit from any country is handled the same way.
What marketers use instead
First-party data
Customer lists, e-mail and phone collected with consent and uploaded to ad platforms. See first-party data.
02Server-side events
Purchases and leads sent from your server so platforms see them without a browser cookie. See Conversions APIs explained.
First-party cookies
Cookies on your own domain, set by your server, that last longer. See extending cookie lifetime.
A simple action list
- Check your site for third-party cookies and note why each exists.
- Move key measurement to first-party and server-side tracking.
- Collect e-mail and phone at checkout and lead forms, with consent.
- Upload customer lists to the ad platforms you use.
- Judge results with your own store numbers.
What this means for a small store
If you run a small shop, the end of third-party cookies is less dramatic than the headlines. You do not rely on a network of publishers. You rely on a few platforms: Meta, Google, perhaps TikTok. Those platforms have their own logged-in users and do much of their matching with first-party data you can supply. What matters for you is to send them good events from your server, with hashed e-mail and phone from checkout, and to keep your own cookies alive. Those two steps cover most of the ground that third-party cookies used to cover.
For larger advertisers who buy across many sites, the picture is harder. They lose some cross-site reach and rely more on platform audiences, contextual targeting and measurement through experiments. If that is you, invest in your own data foundation first, because every alternative builds on it.
Terms you will see
- Third-party cookie
- A cookie set by a domain other than the site you are on.
- First-party data
- Information you collect directly from your own visitors and customers.
- Retargeting
- Showing ads to people who visited your site before.
- Frequency cap
- A limit on how often one person sees the same ad.
- Contextual targeting
- Choosing ads by the content of the page, not by who the person is.
Whatever the browsers decide next, the safe course is the same: make your tracking independent of any single cookie. Events from your server, identifiers you collect with consent and cookies on your own domain keep working when a browser changes a default. Building on those is less of a bet on the future of one vendor’s settings, and it leaves you with data you own and can move between tools.
Ask Ari instead of digging through reports
Ari reads your tracking and ad data and answers in plain words.
Frequently asked questions
What is a third-party cookie?
A cookie set by a domain other than the one in the address bar, often by an ad or analytics network.
Has Chrome removed third-party cookies?
Google planned to, then chose to keep them with existing user controls. Check Chrome's current documentation.
Do third-party cookies still work?
In Chrome often yes, in Safari and Firefox mostly no, and in any browser they fail when users block them.
What replaces them?
First-party data, server-side events, first-party cookies and platform modelling.
Does server-side tracking use third-party cookies?
No. It relies on first-party cookies and data you collect yourself.
Do I need spreadsheets to read my results?
No. Once tracking is live, the Open Tracked analytics shows spend, revenue, ROAS and profit, and you can ask Ari, the built-in AI assistant, questions about your own numbers in plain words. Ari's allowance depends on your analytics plan.
Is Open Tracked different from Open Track or Open Space Track?
No. Open Tracked is the official name of our server-side tracking platform, and the website is opentracked.io. Many people search for it as Open Track, OpenTrack or Open Space Track. All of them lead to the same product: server-side Google Tag Manager hosting, first-party analytics and a CRM pipeline.
Fix your tracking at the source
Open Tracked hosts your server-side Tag Manager, keeps first-party cookies alive and shows what each ad is really worth.
The Open Tracked team
We build Open Tracked: server-side tracking hosting, analytics and the tools around them, for stores that spend on ads. Questions about this guide, or an idea for the next one?
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