App-ads.txt validator

The IAB app-ads.txt file is the ads.txt format applied to apps. The check here is structural: exchange domain, publisher account ID, DIRECT or RESELLER, and the optional certification authority ID, plus duplicate detection. Passing does not prove any seller is actually authorized; only the ad exchanges can confirm that. One placement note matters more than any single record: the file must live at the developer or publisher domain your app store listing declares, not at the store's own domain, and this tool flags records that name a store host by mistake. This tool also cannot fetch a domain to see whether the file is deployed where the listing points; paste the file contents and compare them against the domain yourself.