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.

tractorjunction.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 20 Oct 2026. 6 lines, 4 unique records, 0 duplicates, 0 invalid lines, 2 ad networks detected.

Google AdMob — accounts pub-7687546979319230, pub-3573944675928813: 2 lines in the file
OpenX — account 567341274: 1 line in the file

Yes — https://tractorjunction.com/app-ads.txt has 6 lines (checked 20 Oct 2026).

Its app-ads.txt lists Google AdMob, OpenX.

tractorjunction.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).