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Ads.txt - Authorized Digital Sellers

About Ads.txt and App-Ads.txt

Last updated: January 15, 2024

Ads.txt/App-Ads.txt Version 1.1 To Support Owner and Manager Domains is Ready to Implement

The update includes two new values for publishers to declare within their ads.txt files, “OWNERDOMAIN” and “MANAGERDOMAIN” which helps increase the transparency into seller relationships via sellers.json and further strengthens ads.txt as a tool to reduce fraud in buying and selling of advertisements on websites, mobile apps and connected TV. Read the press release here.

Version History

VersionRelease Date

Ads.txt 1.1

View Implementation Guide


August 2022

Ads.txt 1.0.3

View Explainer Guide


March 2021

Ads.txt 1.0.2

Adds differentiation between ads.txt and app-ads.txt as well as guidance for PLACEHOLDER record

March 2019

Ads.txt 1.0.1

Adds SUBDOMAIN and CONTACT variables

August 2017

Ads.txt 1.0
June 2017


IAB Tech Lab released app-ads.txt version 1.0 as the next step to fight inventory fraud for apps. The app-ads.txt specification is an extension of the original ads.txt standard to meet the requirements for applications distributed through mobile app stores, connected television app stores, or other application distribution channels.  The app-ads.txt final version 1.0 is now available for industry adoption.

Are you buying authorized inventory? Are you looking for an efficient way to access ads.txt file contents?

IAB Tech Lab offers “ads.txt aggregator” – a critical tool to support its ads.txt anti-fraud initiative. This service provides regular updates on publishers’ approved ad sellers, making it easier for marketers, agencies, and platforms to eliminate fraudulent inventory sources, and fight against domain misrepresentation. This tool provides subscribers with access to structured aggregate data files.

Engineers - are you building a crawler to find ads.txt files?

View an open source crawler for ads.txt. This prototype example crawler is given a list of URLs or domains etc and saves them to a SQLite DB table. Please note, this is only an example prototype crawler and would be suitable for a very modest production usage – read more on the github repository.

Open Source Prototype Crawler

Additionally, a reference implementation of app store HTML parsing and app-ads.txt developer URL canonicalization libraries can be found here:

Open Source Ads.Txt Parser

As part of a broader effort to eliminate the ability to profit from counterfeit inventory in the open digital advertising ecosystem, ads.txt provides a mechanism to enable content owners to declare who is authorized to sell their inventory.

Previous Version: ads.txt spec version 1.0.2 | ads.txt Spec Version 1.0 | Blogpost

The Ads.txt Project

The mission of the ads.txt project is simple: Increase transparency in the programmatic advertising ecosystem. ads.txt stands for Authorized Digital Sellers and is a simple, flexible and secure method that publishers and distributors can use to publicly declare the companies they authorize to sell their digital inventory.

By creating a public record of Authorized Digital Sellers, ads.txt will create greater transparency in the inventory supply chain, and give publishers control over their inventory in the market, making it harder for bad actors to profit from selling counterfeit inventory across the ecosystem. As publishers adopt ads.txt, buyers will be able to more easily identify the Authorized Digital Sellers for a participating publisher, allowing brands to have confidence they are buying authentic publisher inventory.

Read more:

The IAB Tech Lab OpenRTB Working Group has developed the ads.txt spec. Questions can be sent to

For more information:

Were you looking for information on sellers.json? Click here to learn more about sellers.json and the OpenRTB SupplyChain Object

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