First-Party vs Third-Party, in One Sentence Each
A first-party cookie is set by the website you're on, under its own domain. A third-party cookie is set by a different domain embedded on that page, typically an ad or tracking service, and has traditionally been used to follow people across many sites.
The technology is the same kind of small file. What differs is who sets it, and that's exactly what browsers now treat differently.
How They Compare
| First-party | Third-party | |
|---|---|---|
| Set by | The site you're visiting | Another domain on the page |
| Typical uses | Logins, carts, preferences, site analytics and tracking | Cross-site ad tracking and retargeting |
| Cross-site tracking | No | Yes, where allowed |
| Safari and Firefox | Allowed, with some limits | Blocked by default |
| Chrome and Edge | Allowed | User controls to limit or block |
How Browsers Treat Them Today
Safari and Firefox block third-party cookies by default. Safari's Intelligent Tracking Prevention also limits how long some cookies set by scripts can last, even first-party ones. Chrome and Edge give users built-in controls to limit or disable third-party tracking.
The direction is clear even where the details differ by browser: tracking that depends on third-party cookies sees less and less, while tracking on your own domain is far more durable.
What This Means for Ad Tracking
- Ad pixels see fewer conversions, especially on Safari and iPhone.
- Retargeting pools shrink because fewer visitors can be added.
- Cross-device journeys break more often.
- Reported ROAS drops even when real sales hold steady.
That's why many advertisers felt their ads "stopped working" when the real change was in what could be measured. See our iOS tracking guide.
How to Move to First-Party Tracking
- Track on your own domainUse a tracker whose code runs as part of your site, not as a third-party script.
- Use a custom tracking domainServe tracking from a subdomain like track.yoursite.com. See our custom tracking domain guide.
- Send conversions from a serverSo platforms receive events even when browser scripts are blocked. See server-side tracking.
- Collect first-party data with consentEmail and phone, used to match conversions, are among the most valuable signals you have.
- Keep UTMs consistentSo first-party tracking knows each visit's source.
Consent Still Matters
First-party doesn't mean exempt. Privacy laws such as GDPR can require consent for cookies used for marketing or analytics regardless of who sets them. Use a consent tool where your audience requires one, and configure your tracking to respect the choices people make.
First-Party Tracking With ClickMagick
ClickMagick says its TrueTracking uses first-party cookies on your own domain and no redirects, so it isn't affected by iOS privacy changes or Safari's tracking prevention the way third-party pixels are. You can serve it from a custom tracking domain, and it sends conversions to Meta, Google, TikTok and Microsoft from its side. See how TrueTracking works.
Move your ad tracking onto your own domain.
Try ClickMagick FreeFrequently Asked Questions
What is a first-party cookie?
A first-party cookie is set by the website you're visiting, on that site's own domain. It's used for things like keeping you logged in, remembering a cart, and first-party analytics or tracking.
What is a third-party cookie?
A third-party cookie is set by a different domain from the site you're visiting, usually an ad or tracking service embedded on the page. It's traditionally used to track people across many websites.
Do browsers block third-party cookies?
Safari and Firefox block third-party cookies by default, and Chrome and Edge give users controls to limit or disable third-party tracking. That's why tracking based on third-party cookies has become less reliable.
Are first-party cookies affected by privacy rules?
Yes. They're treated more favourably by browsers, but laws such as GDPR can still require consent for first-party cookies used for marketing or analytics. Safari also limits the lifespan of some script-set cookies.
How do I move to first-party tracking?
Run tracking on your own domain or a subdomain you control, send conversions from your server where possible, and collect customer data directly, with consent. A tracker that supports a custom tracking domain makes this straightforward.