First-Party Data: Collecting It Without Third-Party Cookies
First-party data is data a site gets directly from its visitors: behavior on the site, registrations, requests, subscriptions, purchases, survey answers. Unlike data from third-party trackers, it is collected on your domain and under your responsibility. The popular claim “third-party cookies are leaving Chrome, so build everything on first-party data” is outdated: in 2025 Google announced that Chrome will maintain its current approach of giving users a choice (restated in an update of 17 October 2025). Below: what is currently known about third-party cookies, how first-party cookies work in GA4, what a server container does, and how to collect your own data through SEO without promises that are not in the documentation.
What is happening with third-party cookies
- Chrome. In the Privacy Sandbox update of 17 October 2025 it says: Chrome will maintain its current approach to offering users third-party cookie choice; some Privacy Sandbox technologies are being phased out (the update on plans). It does not follow that cookies will always be available: they may be blocked by browser restrictions, user settings, developer flags or enterprise policy. The documentation asks you to provide a good experience whether or not they are available.
- Safari. WebKit announced full third-party cookie blocking on 24 March 2020 (Intelligent Tracking Prevention improvements in iOS and iPadOS 13.4 and Safari 13.1; the WebKit blog post).
- Other browsers and extensions. Different browsers have their own restrictions, and they change: check the current rules before implementing rather than relying on a remembered picture.
The conclusion for an analyst: do not build measurement on the assumption that third-party cookies are available, but do not assume they have vanished everywhere either. What is durable is what you collect on your own domain and with consent (privacy and consent).
Types of data
| Type | Source | Note |
|---|---|---|
| First-party | your site and apps: analytics, forms, orders, requests | you decide what to collect, but must meet consent requirements |
| Second-party | a partner’s data passed to you directly | an industry term; needs a contract and a legal basis |
| Third-party | ad networks, external trackers | availability depends on the browser and the user’s settings |
The division “gold standard versus going away” from popular tables is an authors’ assessment, not a documented fact. Search Console data is not among data collected on your site either: it is information about impressions and clicks in Google Search (Search Console for an analyst).
First-party cookies and GA4
The Analytics help page (cookie usage in GA4) says: the GA4 JavaScript tags use first-party cookies to distinguish unique users and sessions; the libraries do not require cookies to transmit data. The main cookies are _ga (distinguishes users, 2 years by default) and _ga_<container-id> (persists session state, 2 years). Browsers limit the lifespan of first-party cookies if a user does not return: a maximum of 400 days in Chrome and 7 days in Safari. So even “your own” cookies are not eternal: a user returning after several weeks in Safari will not be recognized (GA4 overview).
Server-side tagging
A Tag Manager server container runs not in the user’s browser but on a server you control; it receives requests from the user’s device, turns them into events and processes them with tags, triggers and variables. The data is with you, and you decide how to transform it and where to send it (introduction to server-side tagging). The help page advises setting up the container on your own domain. The statement “server-side tagging makes collection independent of blockers” is not found in the help page: it is practice, the effect depends on configuration, and consent requirements remain.
How to grow your own data through SEO
- Subscriptions: checklists, newsletters, mini-courses on the topic that brought the organic traffic.
- Interactive materials: calculators, surveys, checkers — they collect data and engage; but the form’s questions must be needed and explained.
- Registration: free tools or a gated part of the site; the fewer fields, the easier consent.
- Behavior analysis: events on the site and your goals (KPIs in SEO) show which pages lead to requests.
Figures like “800 contacts per quarter” are different in every project, and promises like “retargeting no longer depends on cookies” depend on ad platforms and consents, so they are not in this lesson.
Principles
- Purpose. Collect what a specific decision needs, not everything.
- Consent and transparency. Consent mode applies to your own cookies too: when consent is denied, Google tags do not store cookies.
- Unified identification. Connect analytics, CRM and form data by what the user has shared themselves, and only lawfully.
- Verification. Reconcile sources (GA4, Search Console, CRM) and do not expect an exact match.
Checklist
- Measurement works with third-party cookies available and unavailable.
- It is clear which data is collected on the domain and on what basis.
- The banner and Consent mode are set up; when consent is denied, data is not stored.
- There are as many forms and subscriptions as needed; consent wording is agreed with a lawyer.
- For server-side tagging the container is on your own domain and the effect is checked on data.
- Data sources are reconciled with each other.
Mistakes
- Assuming Chrome has removed third-party cookies: the current approach is user choice.
- Treating first-party cookies as eternal.
- Collecting data without consent “because it is first-party”.
- Expecting server-side tagging to solve the blocker problem on its own.
- Promising a client growth of a contact base or a retargeting effect without your own data.
What next
Next comes international SEO: how to work with several countries and languages and which data to collect for each market.