Third-party cookies are going away. Safari and Firefox blocked them years ago. Chrome has been phasing them out since 2024. For anyone running web analytics, this shift changes how visitor tracking works — and which tools will still give you accurate data.
The distinction between first-party and third-party cookies is simple, but the consequences for analytics are significant.
How Cookies Work
A cookie is a small text file that a website stores in your browser. It contains an identifier — usually a random string — that lets the site recognize you when you come back. Cookies are how a site remembers your login, your shopping cart, or the fact that you've visited before.
The "party" in first-party and third-party refers to who sets the cookie.
First-party cookies are set by the website you're visiting. When you go to example.com and it stores a cookie under example.com, that's first-party. Your browser trusts these because they come from the site you chose to visit.
Third-party cookies are set by a different domain than the one in your address bar. When you visit example.com and an ad network at adtracker.net sets a cookie through an embedded script, that's third-party. The cookie belongs to adtracker.net, not the site you're on.
Why Third-Party Cookies Existed
Third-party cookies powered cross-site tracking. An ad network could place its cookie on thousands of websites, and every time you visited any of them, the network would recognize you. This let advertisers build browsing profiles across the entire web, track conversions across domains, and retarget you with ads based on sites you'd visited days ago.
For analytics, third-party cookies enabled features like:
- Cross-domain tracking without extra configuration
- Attribution across multiple websites owned by the same company
- Ad conversion tracking from the ad platform's perspective
The tradeoff was privacy. Users were tracked across the web without meaningful consent, and the data was used in ways most people didn't understand or approve of.
What Changed
Browsers decided third-party cookies were a privacy problem and started blocking them.
| Browser | Third-Party Cookie Status |
|---|---|
| Safari (ITP) | Blocked since 2020 |
| Firefox (ETP) | Blocked since 2019 |
| Chrome | Phase-out underway since 2024, with Privacy Sandbox as replacement |
| Brave | Blocked by default since launch |
| Edge | Following Chrome's timeline |
Safari also limits first-party cookies set by JavaScript to 7 days (or 24 hours if the visitor arrived from a classified tracking domain). This affects analytics tools that rely on client-side JavaScript to set cookies — which is most of them.
Key Summary
- Third-party cookies are effectively dead across all major browsers
- First-party cookies still work but face shorter lifespans in Safari
- Analytics tools that rely on third-party cookies will lose data on a growing share of visitors
- Server-side tracking and first-party approaches are the path forward
Impact on Analytics
If your analytics tool uses third-party cookies, you've already been losing data. Safari and Firefox users — roughly 30-40% of web traffic depending on your audience — haven't been tracked accurately for years. Chrome's changes extend this to the remaining majority.
The specific problems:
Returning visitors look like new visitors. Without a persistent cookie, each visit from the same person starts a new session with a new identifier. Your "unique visitors" count is inflated. A regular customer who visits three times a week looks like three different people.
Attribution breaks. If a visitor clicks an ad on Monday and comes back to convert on Wednesday, the conversion can't be attributed to the ad without a cookie connecting the two sessions. Your revenue attribution reports will under-credit channels with longer conversion cycles.
Cross-domain tracking fails. Companies with multiple domains (a marketing site, an app, a docs site) rely on cookies to stitch a single visitor's journey across properties. Third-party cookie blocking breaks this chain.
Pageview counts may shift. Some analytics scripts loaded from third-party domains may be blocked entirely by privacy-focused browsers, meaning those visits don't get counted at all.
First-Party Cookies Still Work
First-party cookies — set by the website the visitor is on — remain functional across all browsers. They're considered legitimate because the site you're visiting has a direct relationship with you.
For analytics, this means tools that set cookies under your own domain continue to work. The cookie is yourdomain.com tracking visitors on yourdomain.com, which browsers consider reasonable.
The catch is Safari's 7-day cap on JavaScript-set first-party cookies. A visitor who returns after 8 days gets a new cookie and looks like a new visitor. Server-side cookie setting bypasses this limit because the cookie comes from the HTTP response rather than client-side JavaScript.
Alternatives to Third-Party Cookies
Several approaches have emerged to fill the gap.
Server-side tracking. Instead of relying on client-side JavaScript to set cookies and send data, server-side tracking handles these operations on your web server. Cookies are set via HTTP headers (avoiding Safari's JS limitations), and data is sent directly from your server to the analytics platform. This is more accurate and more resistant to browser restrictions and ad blockers.
Cookieless analytics. Some tools skip cookies entirely and use session-based or event-based tracking. Without cookies, they can't identify returning visitors, but they can accurately count pageviews, traffic sources, and basic engagement. This trades accuracy on visitor-level metrics for complete privacy compliance.
Fingerprinting. Browser fingerprinting identifies visitors by combining device characteristics — screen resolution, installed fonts, browser version, timezone, and more. It works without cookies, but privacy regulators and browsers consider it more invasive than cookies. It's increasingly blocked and is not a viable long-term strategy.
Google's Privacy Sandbox. Chrome's replacement for third-party cookies includes APIs like Topics (interest-based targeting), Attribution Reporting (conversion measurement), and Protected Audiences (retargeting). These are designed for advertisers rather than analytics, and they operate within Chrome only.
What to Do Now
If you're running a website and care about accurate analytics, here's the practical path:
1. Audit your current setup. Check whether your analytics tool uses first-party or third-party cookies. If it loads scripts from a third-party domain and sets cookies under that domain, you're affected.
2. Move to first-party tracking. Use an analytics tool that sets cookies under your own domain. This is the single biggest improvement you can make.
3. Consider server-side cookie setting. If Safari accuracy matters to you (and it should — Safari is the default browser on every iPhone), use a tool that sets cookies server-side or through a CNAME proxy on your domain.
4. Don't rely on fingerprinting. It's unreliable, increasingly blocked, and potentially illegal under GDPR.
5. Accept some data loss. Even with the best setup, some visitors will clear cookies, use private browsing, or block tracking entirely. Design your analytics around trends and patterns rather than exact counts.
Trfyx uses first-party cookies set under your domain, with server-side tracking options available. Visitors are identified with a single-purpose analytics cookie — no cross-site tracking, no third-party dependencies. This approach stays accurate as browsers continue tightening privacy restrictions, because it works within the rules rather than trying to work around them.
The shift away from third-party cookies isn't a temporary inconvenience. It's a permanent change in how the web works. The sooner your analytics adapts, the less data you'll lose in the transition.
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