Ads.txt is an initiative by IAB US aimed at combating domain spoofing and unauthorised reselling.
Domain spoofing works by selling inventory with the URL of a premium website but the truth is the inventory is fed to a less than reputable website. The IAB is encouraging publishers to post a simple text document that lists all the authorised digital sellers for a publisher's inventory. Advertisers can find these lists at publisherssite.com/ads.txt and check the inventory they're buying against it.
Next year, if a publisher adopts ads.txt, AppNexus' DSPs will disable buying from parties that are not directly identified through the publisher’s ads.txt files as authorized resellers.
Its crawler updates on a daily basis to ensure that its default setting is up to date.
This, continued AppNexus, is not an optional filter for buyers using either its legacy DSP, Console, or APP (its newly launched DSP, AppNexus Programmable Platform).
"The new policy will automatically and irrevocably disable buying on unauthorized sellers," Brian O’Kelley, chief executive of AppNexus said in a statement.
The past six weeks have seen a 400% rise in publisher adoption of ads.txt on AppNexus' platform.
"Today, roughly two-thirds of the top one thousand domains directly available on AppNexus’ marketplace have adopted it. We anticipate continued momentum and are confident that by late January we will be able to apply the new standard without disruption to buyers’ or sellers’ business," O’Kelley said.
To help this process along, AppNexus has released a free ads.txt validation tool for public use. The tool will help digital publishers ensure that their ads.txt implementation is free of common errors.