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What is app-ads.txt?

Updated Oct 7, 2026 · data from 12 App Store genres · top free + top grossing charts · US · iOS + Android

Short answerapp-ads.txt is a public text file in which an app developer lists the companies authorized to sell the app's ad inventory. Buyers read it to check that an ad request for an app comes from an authorized seller. It's the mobile version of ads.txt, defined by IAB Tech Lab.

Where it lives

Buyers find it through the developer website in the app's store listing (App Store or Google Play): the file is served at https://<developer domain>/app-ads.txt. One file covers every app that lists that developer website.

What a line looks like

pubmatic.com, 156xxx, RESELLER, 5d62403b186f2ace
  1. Ad system domain: the exchange or SSP the account is on.
  2. Seller ID: the account at that ad system.
  3. Relationship: DIRECT if the publisher controls the account, RESELLER if another company does (see DIRECT vs RESELLER).
  4. Certification authority ID (optional): the ad system's ID with a certification body such as TAG.

Files can also declare variables such as OWNERDOMAIN and MANAGERDOMAIN (explained here) and CONTACT.

How buyers use it

A buyer receives an ad request saying "app X, sold by account Y at exchange Z". It checks that the app's app-ads.txt lists exchange Z with account Y. Then it can look up account Y in exchange Z's sellers.json to see who operates it.

What we see in practice

Across 883 ad-monetized top US apps in this index, 16.0% of seller lines point to accounts that the ad system's own sellers.json doesn't list, and in the typical app 22% of DIRECT lines are inconsistent with public data. Large files often grow by pasting partners' blocks without removing old ones.

Related

Based on the IAB Tech Lab ads.txt/app-ads.txt and sellers.json specifications. Numbers are automated observations of public files on the date above.