An IAB Tech Lab standard that lets app publishers declare which ad networks are authorized to sell their inventory.

Where do I put the app-ads.txt file?

At the root of the developer website listed in your App Store / Google Play page, e.g. https://studio.com/app-ads.txt.

What is a Certification Authority ID?

An optional TAG-ID of the ad system, the 4th field of an app-ads.txt record.

Google AdMob app-ads.txt

AdMob checks the app-ads.txt on the developer website of every app. Your line uses the google.com domain, your pub- publisher ID and Google’s certification authority ID.

Your AdMob line

google.com, pub-<your 16-digit publisher ID>, DIRECT, f08c47fec0942fa0

Find the publisher ID in AdMob under Settings → Account information (pub-XXXXXXXXXXXXXXXX). AdMob also shows the ready line in Apps → View all apps → app-ads.txt → How to set up app-ads.txt — copy it exactly, with DIRECT and the certification ID.

Where the file goes

At the root of the developer website listed on the app’s Google Play / App Store page: https://yourdomain.com/app-ads.txt.
The same domain as in the store listing — a file on another domain or in a sub-folder isn’t found by AdMob.
Plain text, status 200, UTF-8 — not an HTML page, not a redirect to another domain.

Open the free app-ads.txt generator

AdMob mediation

If AdMob mediates other networks (AppLovin, Unity, Meta, Mintegral, Liftoff, Pangle…), each of them needs its own lines in the same file. Without them their bids can’t be verified — mediation doesn’t replace their app-ads.txt lines.

Verification in AdMob

Publish the file and open https://yourdomain.com/app-ads.txt in a browser to make sure it is there.
In AdMob open Apps → View all apps → app-ads.txt and press Check for updates next to the app.
Google re-crawls the file on its own too — the status can take up to a day to change.
If AdMob says the file isn’t found, see fix app-ads.txt not found: most often the developer website in the store listing doesn’t match the domain with the file.

Checklist

One google.com line per AdMob account that serves ads in the app — the pub- ID of that account.
DIRECT for your own account; RESELLER lines only for partners that sell on your behalf.
The certification ID f08c47fec0942fa0 at the end of the line (optional for the standard, expected by Google).
No duplicates and no typos — check your app-ads.txt free to see errors and missing partner lines.

FAQ

What is the AdMob line in app-ads.txt?

google.com, pub-XXXXXXXXXXXXXXXX, DIRECT, f08c47fec0942fa0 — with your own publisher ID from AdMob → Settings → Account information.

What is Google’s certification authority ID?

f08c47fec0942fa0. It is the same for AdMob, Ad Manager and AdSense.

How long does AdMob take to verify app-ads.txt?

Usually within a day. Press “Check for updates” in AdMob → Apps → View all apps → app-ads.txt to ask for a new crawl.

Do I need separate files for Android and iOS?

No. One app-ads.txt on the developer website covers every app that lists that website — on Google Play and the App Store.

Related guides

All app-ads.txt guides