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.

radio-canada.ca achieves the best ad optimization: its app-ads.txt has no errors and matches what its 6 ad networks expect (100% of 8 lines).

Checked 20 Oct 2026. 124 lines, 91 unique records, 1 duplicates, 0 invalid lines, 6 ad networks detected.

Google AdMob — accounts pub-0961408509915763, pub-2477283135655747: 2 lines in the file
Index Exchange — accounts 183773, 187480: 2 lines in the file
Magnite (Rubicon) — accounts 20374, 20376: 2 lines in the file
OpenX — account 540717829: 1 line in the file
Xandr (Microsoft) — account 9117: 1 line in the file
Meta Audience Network — accounts 1556913674642453, 191677467903931, 185153805222964: 3 lines in the file

Yes — https://radio-canada.ca/app-ads.txt has 124 lines (checked 20 Oct 2026).

Its app-ads.txt lists Google AdMob, Index Exchange, Magnite (Rubicon), OpenX, Xandr (Microsoft), Meta Audience Network.

radio-canada.ca achieves the best ad optimization: its app-ads.txt has no errors and matches what its 6 ad networks expect (100% of 8 lines).