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.

investors.com achieves the best ad optimization: its app-ads.txt has no errors and matches what its 8 ad networks expect (100% of 14 lines).

Checked 20 Oct 2026. 63 lines, 31 unique records, 1 duplicates, 0 invalid lines, 8 ad networks detected.

PubMatic — accounts 158676, 162976: 2 lines in the file
Index Exchange — accounts 184947, 185780: 2 lines in the file
Magnite (Rubicon) — accounts 9673, 14474: 2 lines in the file
Yahoo — accounts 58795, 58796, 58966: 3 lines in the file
TripleLift — account 11556-EB: 1 line in the file
OpenX — accounts 540158404, 540793552: 2 lines in the file
Google AdMob — accounts pub-4159017740785598, pub-1460316964194391: 2 lines in the file
Xandr (Microsoft) — account 7214: 1 line in the file

Yes — https://investors.com/app-ads.txt has 63 lines (checked 20 Oct 2026).

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

investors.com achieves the best ad optimization: its app-ads.txt has no errors and matches what its 8 ad networks expect (100% of 14 lines).