What you need to know about Ads.txt

Yair Miranda

Programmatic advertising has done wonders to automate transactions and improve monetization. But it also opened a window to potential unauthorized business. A CNBC article uncovered the harm, forecasting advertisers could face an estimated loss of over $16.4B in 2017, a rise from $12.5 last year.


Ads.txt (Authorized Digital Sellers Project) was initiated by the IAB Tech Lab to help battle fraud and bring back trust and control to the advertising scape. This important initiative is gaining traction and is expected to be mandatory by early next year.

The implementation of Ads.txt is not difficult, but demands a thorough audit to ensure the publisher’s revenue stream is not affected.

How does it work on the publisher side?

Ads.txt requires publishers to drop a file on their web server that lists all the parties authorized to sell or resell the publisher’s inventory. The file lists partners by name, and comes with the publisher’s account ID. The publisher’s ID can be detected by buyers in a bid request and used as a key for buy decisions. Publishers can also specify the relationship they have with each partner – either direct or reseller.

How does it benefit publishers?

Publishers have a lot to gain from Ads.txt. It introduces more transparency and visibility into who is selling their inventory and protects the publisher’s brand from potential damage possibly introduced by unauthorized resellers. The downside is that if the file is not deployed properly, a missing item or a partial file can jeopardize a publisher’s revenue stream.

The opportunity for DSPs

Buyers, primarily DSPs, can use a web crawler released by the IAB Tech Lab to rapidly download all Ads.txt files from the publisher’s sites. This way the buyers can know when they bid on a request from an authorized ID that it comes from a trusted source, with legitimate access to the publisher’s inventory. However authorized traffic does not imply completely free of invalid traffic, and visa-versa. Non-authorized traffic does not necessarily equal invalid traffic, according the IAB

If the inventory is still available on multiple exchanges through legitimate sources, buyers with optimization technology can opt to supply path optimize between publisher accounts, to minimize the bid journey and cut costs.

The state of Ads.txt

Based on our data covering over 1.5M sites, as of Sep 2017, only a few thousand publishers have implemented Ads.txt. We expect this slow adoption to accelerate, as more platforms, including Cedato, are proactively supporting the initiative.

What you need to do now

Here at Cedato our team is available to help you assess your Ads.txt file for accuracy and compliance. Whether you are a publisher or DSP, our Ads.txt support team welcomes any of your queries.