The essential information about ads.txt, its meaning, role and tips on how to implement this simple tool aiming to bring simplicity and clarity to the digital ad market in few quick steps.

What is all the fuss with ads.txt about?

Ads.txt, which stands for Authorized Digital Sellers, is a text file that is implemented in a publisher’s web server to inform those on the buy side about who is selling inventory programmatically. Originally, ads.txt was launched in May 2017 by the IAB to reduce domain spoofing and reselling in the open marketplace.

What main purpose does it serve?

The IAB’s ads.txt was supposed to bring simplicity and clarity to the digital ad market while cutting down on fraud. But so far only a fraction of the world’s top publishers have adopted it.

The file itself is an IAB Tech Lab project developed to eliminate inventory fraud in the digital advertising industry. Just like how robots help search engines understand the contents of a website, the ads.txt helps buyers discover how a website’s inventory is supposed to be sold.

Simply put, the ads.txt lists all the platforms that are authorized to sell the inventory, in terms of all the SSPs used and the specific accounts (seats) run by both the publisher (owned inventory) and resellers (represented inventory) respectively.

This is how ads.txt file looks like at 

This is how ads.txt file looks like

How is ads.txt trending among the publishers?

The anti-ad-spoofing tool wasn’t as well received as initially expected. An open letter to publishers about ads.txt recently released on Digiday says it all: ‘Adopt or be blocked’.

Yet, publishers aren’t rushing to adopt ads.txt, even though the tool was launched to “help ad buyers avoid illegitimate sellers that arbitrage inventory and spoof domains”, and simultaneously help publishers sell their inventory more effectively.

Grasping it all with clarity does take some time. Many publishers don’t seem to understand how they can benefit from ads.txt. But apart from a clear case of a lacking awareness, there’s also a much darker side to it. Some publishers aren’t that willing to notify ad buyers that they rely on unauthorized resellers to drive demand for their inventory.

It’s no wonder that, according to MarTech Today, only 34 out of the 500 most-trafficked sites in the U.S. use ads.txt so far.

Why should you implement it?

Unfortunately, publishers see no direct benefit of the ads.txt implementation. At least for now. Some buyers are already using the file in search for reliable and high-quality inventory. Our experts at Yieldbird expect buyers to eventually stop spending on sites that don’t have the ads.txt file implemented.

Just like how they moved away from spending on sites that don’t provide full URL transparency.

How will the ad tech ecosystem respond to ads.txt?

It’s difficult to say at this point. Whether or not publishers adopt ads.txt or take the risk of being blocked, experts expect that this initiative will gain momentum in the near future.


Most of the leading SSPs are already advising publishers to use the ads.txt file. The major DSPs are also expected to use this information and maybe even block domains that don’t have the file yet.

But even if that’s not going to be the case, some of the bigger buyer networks may implement their own crawlers to go through the domains and build their own custom whitelists.

So far, the ads.txt has been implemented by several publishers, such as The Guardian  or Agora S.A. But the statistics show that no more than 12.8% of publishers have an ads.txt file implemented so far, according to the Ad Ops Insider. Some of the big players are joining the game with some stats and clarifications to ease the new-standard-adoption pain.

DoubleClick Advertiser also decided to do some research to clear up any doubt or misconception about video ad viewability rates around the world and across devices.


Just get in touch with the SSPs you’re using to see what should be put in the ads.txt file. It’s possible that you already received the e-mail containing this information in the past few weeks.

On top of that, some of the SSPs have already published their own guidelines. Here’s one provided by Google.

If you find it easier to go step by step with our experts, check out the QUICK GUIDE TO ADS.TXT IMPLEMENTATION to fully grasp the ads.txt file.


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