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.

gmx.net app-ads.txt check

gmx.net achieves the best ad optimization: its app-ads.txt has no errors and matches what its 9 ad networks expect (100% of 18 lines).

Checked 19 Oct 2026. 144 lines, 87 unique records, 0 duplicates, 0 invalid lines, 11 ad networks detected.

Ad networks in gmx.net/app-ads.txt

Xandr (Microsoft) — account 1578: 1 line in the file
Amazon Publisher Services — account 3206: 1 line in the file
PubMatic — accounts 157878, 160293, 158076 and 1 more: 4 lines in the file
Magnite (Rubicon) — account 21240: 1 line in the file
TripleLift — account 6004: 1 line in the file
OpenX — accounts 564176750, 540690262, 540791457: 3 lines in the file
Google AdMob — account pub-8493805572411343: 1 line in the file
Index Exchange — accounts 189131, 189890, 193286 and 2 more: 5 lines in the file
Meta Audience Network — account 703363157350687: 1 line in the file
Yango Ads — partner (reseller) lines only: 11 lines in the file, 400 expected lines missing
Bidmachine — partner (reseller) lines only: 12 lines in the file, 400 expected lines missing

Corrected file: gmx.net app-ads.txt (fixed).

FAQ

Does gmx.net have an app-ads.txt?

Yes — https://gmx.net/app-ads.txt has 144 lines (checked 19 Oct 2026).

Which ad networks does gmx.net work with?

Its app-ads.txt lists Xandr (Microsoft), Amazon Publisher Services, PubMatic, Magnite (Rubicon), TripleLift, OpenX, Google AdMob, Index Exchange, Meta Audience Network, Yango Ads, Bidmachine.

Is the app-ads.txt of gmx.net correct?