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.

dropsonline.de achieves the best ad optimization: its app-ads.txt has no errors and matches what its 7 ad networks expect (100% of 12 lines).

Checked 20 Oct 2026. 37 lines, 29 unique records, 0 duplicates, 0 invalid lines, 7 ad networks detected.

Xandr (Microsoft) — account 9160: 1 line in the file
Google AdMob — accounts pub-1772393173576368, pub-3345820264133058, pub-4339208846845271 and 2 more: 5 lines in the file
Index Exchange — accounts 186024, 210471: 2 lines in the file
OpenX — account 539808723: 1 line in the file
PubMatic — accounts 157252, 160101, 157743: 3 lines in the file
Magnite (Rubicon) — accounts 19692, 19694, 17280: 3 lines in the file
TripleLift — account 11451-EB: 1 line in the file

Yes — https://dropsonline.de/app-ads.txt has 37 lines (checked 20 Oct 2026).

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

dropsonline.de achieves the best ad optimization: its app-ads.txt has no errors and matches what its 7 ad networks expect (100% of 12 lines).