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.

accuweather.com achieves the best ad optimization: its app-ads.txt has no errors and matches what its 8 ad networks expect (100% of 17 lines).

Checked 20 Oct 2026. 82 lines, 28 unique records, 0 duplicates, 0 invalid lines, 8 ad networks detected.

Google AdMob — accounts pub-9415735639897500, pub-5771594739411148: 2 lines in the file
Xandr (Microsoft) — account 8997: 1 line in the file
Index Exchange — accounts 185017, 185474, 214466: 3 lines in the file
Magnite (Rubicon) — account 12562: 1 line in the file
OpenX — accounts 539014228, 565130139, 539513282 and 1 more: 4 lines in the file
Yahoo — account 57307: 1 line in the file
PubMatic — accounts 34576, 157374: 2 lines in the file
TripleLift — accounts 2895, 6873, 2895-EB and 1 more: 4 lines in the file

Yes — https://accuweather.com/app-ads.txt has 82 lines (checked 20 Oct 2026).

Its app-ads.txt lists Google AdMob, Xandr (Microsoft), Index Exchange, Magnite (Rubicon), OpenX, Yahoo, PubMatic, TripleLift.

accuweather.com achieves the best ad optimization: its app-ads.txt has no errors and matches what its 8 ad networks expect (100% of 17 lines).