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.

gumtree.com app-ads.txt check

gumtree.com achieves the best ad optimization: its app-ads.txt has no errors and matches what its 9 ad networks expect (100% of 19 lines).

Checked 19 Oct 2026. 66 lines, 45 unique records, 2 duplicates, 0 invalid lines, 9 ad networks detected.

Ad networks in gumtree.com/app-ads.txt

Google AdMob — account pub-5105067122536534: 1 line in the file
Xandr (Microsoft) — account 7634: 1 line in the file
Index Exchange — accounts 185523, 186893, 207009: 3 lines in the file
PubMatic — accounts 156407, 157155, 162560: 3 lines in the file
Magnite (Rubicon) — accounts 13948, 18478: 2 lines in the file
Criteo — account B-061831: 1 line in the file
OpenX — accounts 565050706, 539108728, 564176683 and 1 more: 4 lines in the file
TripleLift — accounts 2989, 2989-EB: 2 lines in the file
Amazon Publisher Services — accounts bfadd899-b592-4d36-89d8-fcbf3bcddb32, 5087: 2 lines in the file

Corrected file: gumtree.com app-ads.txt (fixed).

FAQ

Does gumtree.com have an app-ads.txt?

Yes — https://gumtree.com/app-ads.txt has 66 lines (checked 19 Oct 2026).

Which ad networks does gumtree.com work with?

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

Is the app-ads.txt of gumtree.com correct?