Ads.txt: Latest Defence Against Ad Fraud Could Save Marketers Millions

People sitting at a desk

As digital advertising investment soars, ad tech continues to be a leaky boat riddled with fraud and brand safety issues. But the tides are changing. Here’s everything you need to know about ads.txt, the latest tool in the fight against programmatic ad fraud.

What is Ads.txt

Ads.txt is a digital marketer’s best friend. It’s a simple and sleek tool that fights one of the most common forms of fraud: Domain spoofing. On a basic level, ads.txt is a text file placed on a publisher site listing all of the exchanges the publication works with and the type of inventory those exchanges support.

The tool allows buyers to filter out imposter domains by ensuring their advertising software (DSP) is using this ads.txt file as part of their quality assurance initiatives, especially for popular sites.

This way, marketing dollars aren’t wasted on fraudulent domains posing as major league publishers. Major publishers (ironically considered the safest sites due to their credibility) are often targeted by cybercriminals due to the high price of inventory. It’s like robbing a major bank rather than a corner store.

According to IAB, “The mission of the ads.txt project is simple: Increase transparency in the programmatic advertising ecosystem. Ads.txt stands for Authorized Digital Sellers and is a simple, flexible and secure method that publishers and distributors can use to publicly declare the companies they authorize to sell their digital inventory.”.

What This Means for Advertisers

Less waste! To say ads.txt can prevent billions of dollars being lost to wasted ad budgets is true. But it also preserves the hard work of agency creatives who generated the ad, and digital marketers and media buyers who strategized and ran the campaign. If you factor (wo)man-power into the cost of misplaced ads, the savings are astronomical.

Is Domain Spoofing Really a Problem?

According to a report by Digiday, the Financial Times recently discovered fraudulent inventory of over $1 Million dollars per month. “We are working with partners to support the adoption of ads.txt by all publishers, as part of our ongoing efforts to help clean up digital advertising,” said Jon Slade,’s Chief Commercial Officer.

Earlier this year, over 6,000 premium domains were spoofed in a breach now known as the Methbot Scheme. This initiative, led by a Russian cybercrime ring, generated as much as $5 Million in revenue per day

Short answer, yes.

How Ads.txt Works

Engineers employed by publishers drop a simple text file onto their domain using an “ads.txt” URL. For example, if you want to see Forbes’ list of valid exchange partners, simply type into your browser and this will pop up:


Your DSP’s QA team will use this list to flag any suspicious exchanges during the ad audit process, ensuring your ad and budget are channeled to the authentic site rather than a spoofed domain.

While this process is currently manual, sites will likely be crawled automatically in the near future.

Are Publishers Adopting Ads.txt

As of September 6th, 2017: “Of the 500 most-trafficked sites in the US, only 34 use ads.txt, according to a recent analysis by MarTech Today,” cited Digiday. However, this number is said to be increasing rapidly.

In the publishing world, ad fraud is often on the back burner for overloaded and time constrained engineers. As advertisers, it is our job to champion the benefits of this new tool and put pressure on the publishing industry to speed up adoption.

Taking Action

Ads forwarded to fraudulent sites should affect publisher credibility. But this will only affect ad sales if buyers choose to blacklist sites who haven’t instituted basic measures of protection.

Ned Dimitrov
Ned Dimitrov

VP of Data Science


Dr. Dimitrov leads the data science team, which creates novel algorithms for advertisement delivery using vast amounts of historical and real-time information. Before StackAdapt, he was a professor in Operations Research at The University of Texas at Austin.