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.

stockx.com achieves the best ad optimization: its app-ads.txt has no errors and matches what its 2 ad networks expect (100% of 2 lines).

Checked 22 Oct 2026. 40 lines, 28 unique records, 0 duplicates, 0 invalid lines, 6 ad networks detected.

Google AdMob — account pub-7081191471292097: 1 line in the file
OpenX — account 561532308: 1 line in the file
Mintegral — partner (reseller) lines only: 11 lines in the file, 400 expected lines missing
Yango Ads — partner (reseller) lines only: 12 lines in the file, 400 expected lines missing
DSP Exchange — partner (reseller) lines only: 17 lines in the file, 400 expected lines missing
Bidmachine — partner (reseller) lines only: 18 lines in the file, 400 expected lines missing

Yes — https://stockx.com/app-ads.txt has 40 lines (checked 22 Oct 2026).

Its app-ads.txt lists Google AdMob, OpenX, Mintegral, Yango Ads, DSP Exchange, Bidmachine.

stockx.com achieves the best ad optimization: its app-ads.txt has no errors and matches what its 2 ad networks expect (100% of 2 lines).