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.

appannex.com achieves the best ad optimization: its app-ads.txt has no errors and matches what its 4 ad networks expect (100% of 4 lines).

Checked 19 Oct 2026. 33 lines, 30 unique records, 0 duplicates, 0 invalid lines, 5 ad networks detected.

Google AdMob — accounts pub-7983928967166090, pub-3940256099942544: 2 lines in the file
Meta Audience Network — account 541540213283248: 1 line in the file
OpenX — account 557059923: 1 line in the file
Smaato — account 1100051378: 1 line in the file
DSP Exchange — partner (reseller) lines only: 13 lines in the file, 400 expected lines missing

Yes — https://appannex.com/app-ads.txt has 33 lines (checked 19 Oct 2026).

Its app-ads.txt lists Google AdMob, Meta Audience Network, OpenX, Smaato, DSP Exchange.

appannex.com achieves the best ad optimization: its app-ads.txt has no errors and matches what its 4 ad networks expect (100% of 4 lines).