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.

spreaker.com achieves the best ad optimization: its app-ads.txt has no errors and matches what its ad network expects (100% of 1 line).

Checked 21 Oct 2026. 215 lines, 124 unique records, 0 duplicates, 0 invalid lines, 3 ad networks detected.

Magnite (Rubicon) — account 22448: 1 line in the file
DSP Exchange — partner (reseller) lines only: 14 lines in the file, 400 expected lines missing
Bidmachine — partner (reseller) lines only: 12 lines in the file, 400 expected lines missing

Yes — https://spreaker.com/app-ads.txt has 215 lines (checked 21 Oct 2026).

Its app-ads.txt lists Magnite (Rubicon), DSP Exchange, Bidmachine.

spreaker.com achieves the best ad optimization: its app-ads.txt has no errors and matches what its ad network expects (100% of 1 line).