IAB Tech Lab has introduced a beta version of the ads.txt protocol specification specific for mobile applications. It will be open for public discussion until February 4.

New app-ads.txt file allows app developers to verify their inventory – just as site owners can. It lists the names and identification codes of all authorized sellers of the advertising inventory available in the app. As a result of the implementation of this Protocol, advertisers will only be able to bid on mobile placements from those sellers listed in the file.
The first version of app-ads.txt was introduced in June, but it outlined only possible approaches to the implementation of the ads Protocol.txt for applications. The current version already describes a specific approach that relies on app stores. Recall that the new tool to combat fraud in programmatic-ads.txt – was first introduced in may 2017. And in July of the same year, IAB Tech Lab published the final version of this Protocol for websites.
The purpose of the ads.txt is to eliminate fraud and increase transparency in programmatic by registering authorized ad sellers and removing illegitimate sellers from the supply chain.