In this guide
- The Protected Audience API (earlier called FLEDGE) was a Privacy Sandbox proposal for remarketing inside the browser, without third-party cookies.
- In October 2025 Google announced it would retire most Privacy Sandbox technologies, Protected Audience included, citing low adoption.
- The practical answer for advertisers is first-party audiences: your own customer lists, server events and consented identifiers.
For years, the plan for the end of third-party cookies had a name: the Privacy Sandbox. It was a group of browser APIs meant to replace the jobs that cookies did, such as remarketing, measuring conversions and interest-based ads. The Protected Audience API was the remarketing piece. This page explains how it worked, what happened to it and what that means for you. Sources: Google's retirement announcement as reported by PPC Land and the Chromium intent to remove thread.
What problem it tried to solve
Classic remarketing works like this: a visitor looks at a pair of shoes, an ad network drops a third-party cookie, and later on another site the network recognises the cookie and shows the shoes. That requires a cookie that follows the person across sites, which is exactly what browsers started to block. Protected Audience proposed to keep the useful part (showing a relevant ad) and remove the tracking part (an identifier that follows you).
Brands that grow on cleaner data
Stores and agencies use Open Tracked to see which ads earn the sale.
How it was designed to work
The browser joins an interest group
When you view the shoes, your site asks the browser to add you to a group, for example "viewed running shoes". The list is stored on the device, not on a server.
A page requests an ad
Later, on a publisher's page, the page asks the browser to run an ad auction.
The auction runs on the device
The browser collects bids from the advertisers whose interest groups you belong to and picks a winner locally. The publisher and advertisers do not see your list.
The ad is shown in a sealed frame
The page cannot read which ad won or why. Reporting was meant to happen through other aggregated APIs.
Why it did not take off
- Complexity. Advertisers and ad platforms had to rebuild bidding logic to run inside a browser sandbox.
- Chrome kept third-party cookies. After several delays Chrome moved away from removing them by default, which removed the pressure to adopt a replacement.
- Low usage. Chromium's own removal proposal noted that use of the join and auction calls had fallen sharply, and almost no auctions produced winners.
- Measurement gaps. Advertisers still needed reporting and attribution that the other proposed APIs did not fully deliver.
In October 2025 Google announced it would retire most Privacy Sandbox technologies, and Chrome filed an intent to deprecate and remove Protected Audience. As of this writing, check Chrome's platform status page for the exact removal timeline. Google said it would keep a small number of privacy features, such as CHIPS (partitioned cookies).
Ask Ari instead of digging through reports
Ari reads your tracking and ad data and answers in plain words.
What advertisers use instead
Customer lists
Upload hashed e-mail and phone lists to Google Ads, Meta and TikTok and build audiences from them. See customer list in Google Ads.
02Server-side events
Send purchases and leads from your server with the Conversions API so platforms can learn who converts. See Conversions API explained.
Consent and Consent Mode
Use the visitor's choice to decide what is sent, and let Google model the rest. See Consent Mode v2.
Your own analytics
Judge campaigns by revenue and profit in your own data, not by a single platform's attribution.
What to do this quarter
- Stop planning around Protected Audience or other retired Privacy Sandbox APIs.
- Send every purchase and lead from the server, with an event ID shared with the browser event.
- Collect e-mail and phone at checkout and lead forms, with clear consent.
- Keep the platform cookies alive from your own subdomain. See extending cookie lifetime.
- Check your audiences in each platform and rebuild them from first-party lists.
How Open Tracked helps
The parts of this plan that need a server are available on every Open Tracked plan, including Free: the tagging server, Cookie Keeper for long-lived cookies, the Data Store and Enricher, which add stored hashed e-mail and phone to later events, and Visitor Location. The analytics product then shows spend, revenue, ROAS and profit next to the tracking, so you can judge audiences by money rather than platform-reported numbers.
A short timeline
| When | What happened |
|---|---|
| 2020 | Google proposed the Privacy Sandbox as a set of browser APIs to replace third-party cookie uses. |
| 2022 | The remarketing proposal was renamed from FLEDGE to the Protected Audience API. |
| 2024 | Chrome delayed and then changed its plan: user choice instead of a default removal of third-party cookies. |
| October 2025 | Google announced that most Privacy Sandbox technologies, Protected Audience among them, would be retired after low adoption. |
| After that | Chrome published an intent to remove the API; advertisers kept using first-party data and server events. |
Dates for browser changes move often. Treat this table as a guide to the direction of travel, and check the primary sources linked above for the current status.
What this means for each team
Store owners
Nothing to install. Make sure purchases are sent from your server and that your customer lists are uploaded to the ad platforms you use.
Agencies
Remove "prepare for Protected Audience" from your roadmap. Offer first-party audiences and server events as the standard package.
Developers
You do not need to build interest group or auction code. Spend the time on the data layer, the event IDs and consent.
Questions to ask a vendor who still mentions it
- Which of your features depend on the Protected Audience API?
- What replaces them now that Google has announced its retirement?
- Can the same audiences be built from my own customer data?
- What do you need from me to send server events?
Raw events in. Clean events out.
Open Tracked collects each event on your own domain, removes the noise and sends what is left to Meta, Google Ads, TikTok.
Frequently asked questions
Is Protected Audience still available?
Google announced in October 2025 that it would retire it, and Chrome has a published intent to remove it. Check Chrome's platform status for the current state.
What was FLEDGE?
FLEDGE was the earlier name of the Protected Audience API.
Does the end of the Privacy Sandbox mean third-party cookies are back?
Chrome has kept them available with user controls rather than removing them, but Safari and Firefox block them and many users and tools block them too. Do not rely on them.
What replaces remarketing without cookies?
Audiences built from your first-party data: customer lists, server events and consented identifiers.
Do I need to do anything for the Protected Audience API?
No. If you had experiments with it, you can retire them. Spend the effort on first-party data instead.
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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