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.

theglobeandmail.com achieves the best ad optimization: its app-ads.txt has no errors and matches what its 6 ad networks expect (100% of 10 lines).

Checked 20 Oct 2026. 49 lines, 43 unique records, 0 duplicates, 0 invalid lines, 6 ad networks detected.

Google AdMob — account pub-3746578658400510: 1 line in the file
Xandr (Microsoft) — accounts 1285, 1985084: 2 lines in the file
Index Exchange — accounts 181495, 185292, 194226: 3 lines in the file
Amazon Publisher Services — accounts 3947, db35412e-0c26-4174-afac-325b525f38fe: 2 lines in the file
Magnite (Rubicon) — account 24730: 1 line in the file
Smaato — account 1100039310: 1 line in the file

Yes — https://theglobeandmail.com/app-ads.txt has 49 lines (checked 20 Oct 2026).

Its app-ads.txt lists Google AdMob, Xandr (Microsoft), Index Exchange, Amazon Publisher Services, Magnite (Rubicon), Smaato.

theglobeandmail.com achieves the best ad optimization: its app-ads.txt has no errors and matches what its 6 ad networks expect (100% of 10 lines).