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Ads.txt FAQ for Buyers

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What is ads.txt? 

Ads.txt (also known as Authorized Digital Sellers) is an IAB initiative aimed to help prevent unauthorized inventory sales. Publishers drop a text file on their web servers that lists all of the resellers that are authorized to sell the publishers’ inventory. Similarly, programmatic platforms also integrate ads.txt files to confirm which publishers’ inventory they are authorized to sell. This allows buyers to check the validity of the inventory they purchase.

Why did the the IAB implement ads.txt? 

Unauthorized reselling is a major concern in programmatic advertising, and unless buyers contacted publishers directly, they would have had no way of knowing which SSPs are authorized to sell a particular publisher’s inventory. With Ads.txt, the industry has created a quick, easy way for buyers to know which programmatic firms have legitimate access to the inventory they want to buy.

How is AppNexus approaching ads.txt implementation? 

AppNexus is using ads.txt files as the source of truth for who is authorized to sell a given domain. We're currently working closely with our publisher partners to ensure their files are accurate and up-to-date, and subsequently blocking unauthorized resale on our platform.

How easy is ads.txt for a publisher to implement?

Very easy. It is as simple as posting a text file to a publisher's domain similar to what virtually every website already does today with their robots.txt file. Additionally, we recently released a free Ads.txt validation tool to the public. This free resource will help digital publishers ensure their ads.txt files are free of errors.

What percent of pubs (especially top 200 pubs) have implemented ads.txt already? Where can I get an up-to-date list? 

Adoption is rising quickly, with 77 percent of the top 1,000 domains on AppNexus having adopted ads.txt already. This figure is likely to increase in 2018. Because ads.txt has been developed and publicized by the IAB, AppNexus expects and encourages all publishers and exchanges to adopt this standard, as it is in publishers' best interests to do so.

Does AppNexus enforce direct versus reseller declarations? 

No. Publishers control the content of their own files. They are responsible for their accuracy. 

How often does AppNexus' crawler update?


What if I buy external from AppNexus? Does a publisher have to list Rubicon's AppNexus seat for it to be an authorized path?  

No, as long as Rubicon is an authorized path, we will note an implied relationship for Rubicon's APN seat for Console buyers. 

Are publishers who have an ads.txt file posted more legitimate or trustworthy than those that do not?

No, not really, but ads.txt use is strongly encouraged. Publishers are free to decide when and if they post an ads.txt file and those that have posted them reflect a wide range of web content. 

When is ads.txt being being enforced by AppNexus?

Starting Jan 24, for those publishers that have ads.txt implemented, AppNexus will only buy from authorized monetization partners. 

Will AppNexus' adoption of ads.txt impact Deals or external demand?


What does that mean for me as a buyer? Do I have to do anything?

No. Buyers don't have to do anything. Publishers only list sellers in their ads.txt file and do not need to list any sort of buyer ID from any platform, including AppNexus. APP will automatically use ads.txt to filter out Publisher who are not authorized to sell a domain, and if a publisher does not have ads.txt implemented, we will not do anything.

If I buy on AppNexus, am I only buying on Ads.txt enabled domains? 

If a publisher has an ads.txt file, we will thoroughly enforce it and only purchase from authorized monetization partners. If they don't (for example in-app traffic), we won't exclude them from being purchased but will continue to recommend that all publishers adopt ads.txt at the earliest opportunity. 

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