What is ads.txt?

What is ads.txt - Ad Fraud Prevention

As programmatic advertising became mainstream, ad fraud peaked with it costing brands billions annually. As the year comes to an end, ad fraud is once again expected to boom as marketers dump their remaining budget into digital advertising. Cybersecurity firm White Ops have in fact warned that almost half of all ad fraud in 2017 will take place within the final quarter, which could result in £2.6 billion of advertising spend going to waste.

To combat the ongoing growth of ad fraud, the IAB launched the ads.txt project with the simple goal of preventing ad exchanges selling unauthorised advertising space to brands. In doing so, the IAB hopes to bring an end to the selling of arbitrage inventory and domain spoofing.

For those unfamiliar with the initiative, the way in which ads.text helps combat ad fraud can be mystifying to say the least. Within this article, therefore, we’ll be answering the big questions surrounding the technology and how it could improve the efficiency of your brand’s advertising campaigns.

What is ads.txt?

ads.txt is a text file which sits on the website server of a publisher such as the Huffington Post. This text file confirms which ad exchanges have approval to sell advertising space on their website. Advertising exchanges will also integrate with ads.txt to confirm which publishers’ advertising space they are authorised to sell.

How do I access the file?

If a website has an ads.txt file it can be accessed by adding /ads.txt to the end of their domain in most cases. Buzzfeed’s ads.txt file, for example, can be viewed at https://www.buzzfeed.com/ads.txt. Here you’ll find a list of which ad exchanges, such as Index Exchange, have permission to sell advertising space on their website. The ads.txt file also confirms the relationship between the ad exchange and publisher, such as whether they sell directly through the exchange or whether the exchange is a reseller.

How can I monitor a publishers ads.txt file?

https://www.adstxtvalidator.com allows you to view the ads.txt file of any domain in a single location. It also allows you to set-up automated emails allerting you of any changes to a publishers ads.txt file. Their emails can also make you aware of any issues that could result in ad fraud, such as domain spoofing.

Which publishers have adopted the technology?

Whilst some have argued that publishers have been slow to adopt ads.txt, there are a number of major sites confirming which ad exchanges have permission to sell space on their website through ads.txt. A handful of these include BBC News, The Guardian, Mail Online, Huffington Post, The New York Times, CNN, The Washington Post, The Wall Street Journal and Buzzfeed.

Why does ads.txt matter?

Billions in advertising spend is wasted every year when brands buy advertising space from unauthorised sellers. When you buy advertising space from such a seller, say to appear on The Guardian, your adverts will never appear on The Guardian website. ads.txt allows advertisers to confirm which ad exchanges are authorised to sell advertising space on a publisher’s website without having to contact them directly.

Could it fail?

The greatest risk to the ads.txt project is a lack of adoption amongst both publishers and ad exchanges. After all, in order for it to be fail-safe it must be integrated en masse by both large and small players in the advertising industry. Whilst large publishers, such as those listed above, have been quick to adopt the technology there is a lot of work to be done before it is ‘industry-wide’.


In conclusion, ads.txt is the first major initiative to combat ad fraud. As experts in agency selection and auditing, we’ve witnessed first hand the negative impact such waste can have on the success of a brand’s marketing activities and distrust it can cause to form between brands, publishers and agencies.

Moving forward, therefore, it is wise to view a publisher’s ads.txt file before buying advertising space through an exchange. If the seller doesn’t appear, don’t complete your transaction and speak to the publisher directly. The likelihood is that the advertising space you are buying is fraudulent.

If you are a publisher, the below video from Smart walks you through the quick process of implementing a ads.txt file on your website. You can also find out more about implementing ads.txt on the IAB website, where you’ll also find the specs for the latest version of ads.txt.

By | 2017-11-05T23:11:17+00:00 November 4th, 2017|Innovation, Transparency|

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