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How errors in ads.txt files are harming publisher revenue: What can be done?

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The Interactive Advertising Bureau (IAB) Tech Lab introduced ads.txt last year to help ad buyers avoid illegitimate sellers who arbitrage inventory and spoof domains, following calls from across the sector to clean up the supply chain.

The idea is simple: publishers drop a text file on their web servers that lists all of the companies that are authorised to sell their inventory. Similarly, programmatic platforms also integrate ads.txt files to confirm which publishers’ inventory they are authorised to sell. This allows buyers to check the validity of the inventory they purchase.

Sounds great, but sadly things have been falling short and this is causing publishers to lose revenue. According to an article in eMarketer, while adoption of ads.txt among the top 5,000 websites worldwide selling programmatic ads had increased, 16% of those using ads.txt had errors in their files.

Jonathon Shaevitz, President of Industry Index, says that in his company’s experience, things could actually be a lot worse. “We look at about 325,000 ads.txt files a week, and we’re seeing a lot of variation. We looked at the top 5,000 publishers based on Quantcast rankings, and on average we see nine errors per ads.txt file. But there’s a huge variation in that with some companies having 50 errors and others having zero.”

One of the big issues with ads.txt is that it’s a manual process, and publishers are struggling to find the resources to do this properly, which is leading to simple and potentially easily avoidable mistakes.

“We’re finding a huge number of simple spelling errors in the files,” says Shaevitz. “For example, we see around 15,000 publishers, misspell SpotX. This means these publishers are potentially missing out on revenue from the biggest video ad exchange.”

Shaevitz explains that they also see a lot of things listed that simply aren’t demand sources or are not demand sources they’ve ever been able to validate. “This is where fraudulent players are still creeping in,” he says. “We’re looking at these files and we’re seeing the same names getting added quickly. So we’re trying to create some sort of way to identify them. It’s hard to say with 100% certainty that they’re fraudulent, but what we can say is that we’re not able to verify them.”

So who’s making the most mistakes?

“The top 50 publishers have basically 20% fewer errors, but they are also keeping a much tighter check on the number of records that they have in their ads.txt files,” explains Shaevitz. “They’re averaging around 84 entries, whereas the average overall is 150. Not only is this reducing the error and warning rates, it is also allowing pages to load faster.”

There’s a very real revenue incentive for publishers to get things right. “If publishers have made an error with Google, and Google represents 50% of their demand. That’s a lot of money,” says Shaevitz. “Whereas if they made an error with a smaller, more obscure demand partner, it might not mean a lot. But what we see is that there’s a growing use of ads.txt on the buy side.”

Publisher solutions specialist Sovrn recently reached out to its customers to put a figure on what publishers are missing out on. “We realized that a lot of our publishers did not have our Google EBDA (Exchange Bidding in Dynamic Allocation) entry properly put into their files,” explains Anna Carpinello, Associate Operations Support Engineer. “So we reached out to all of those publishers to get this corrected.”

Of those that then updated the file we had reports of 40 to 50% increase in revenue just by that small change alone.”

Carpinello continues: “Just because a publisher has an inaccurate ads.txt file, that doesn’t mean that they’re going to lose all of their revenue, at least not yet. However, there are a couple of really big partners right now that are actively not buying on files with either incorrect information or no information at all. There are other buyers that are still hesitant to behave that way, but we’re seeing this trend start to move in that direction.”

If Jessica Kerwin’s comments from a recent Digiday article are anything to go by, that trend could be about to pick up pace. Advertisers’ enforcement of ads.txt in the open marketplace had been hampered by the question of whether enough publishers have uploaded ads.txt files. But that question has been answered. “We’ve reached critical mass,” said the director of media technology standards at Publicis Media Precision.

The article goes on to quote research from ad tech firm OpenX, which found that 60% of comScore’s top 1,000 publishers in the US have uploaded ads.txt to their sites. Google, which in November 2017 began using ads.txt files to filter out unauthorized inventory, has seen publisher adoption increase and the company is strengthening enforcement. In January, roughly 164,000 sites had uploaded ads.txt files; now, the figure has surpassed 600,000 domains, according to Google’s head of GDPR and data trust, Pooja Kapoor.

So what can publishers do?

Review your ads.txt files regularly

“When we look at the types of errors creeping in,” says Shaevitz, “we see that they persist over a long period of time. This is because smaller publishers usually only update their ads.txt file once a month, sometimes even once every two months, whereas the larger companies update at least weekly. This means that if they have an error they’re catching it, improving on it and ultimately seeing a lot fewer failed bids.”

Be diligent with your requests

Publishers need to be diligent and think about who they’re actually listing. “Breitbart media has 370 companies listed on its ads.txt file,” says Shaevitz. “What that says to us is that they’ll list anybody and that’s just a mistake. Not only is it difficult to manage effectively but also it’s easy for fraudulent suppliers to creep in.” At the other end of the scale he cites the New York Times that has just 17 companies listed.

Don’t assume…

This is a very manual process, so don’t assume that last week’s file was correct and just add to it. This is how errors persist. Check it every time. This means publishers need to put the time into it. This is not a huge problem to solve, you don’t have to install any new technology, publishers just need be more careful.

Keep it clean

“Some of these publishers just keep adding suppliers and all of a sudden find they have a massive list,” says Shaevitz. “USA Today has 363 demand partners listed. I mean, that’s not true. They probably have 25 that represent 90-something percent of their demand. But they obviously are just adding anyone who wants to be at it thinking they’re going to get more revenue.”

Get the knowledge

“At the end of the day bigger publishers have more resources to allocate towards this,” says Carpinello. “This also tends to mean they are more knowledgeable about ads.txt, but more importantly, the more access they have to really granular reporting metrics. And it’s those reporting metrics that really helps to show the revenue impact. This is definitely an area where smaller publishers can learn from their larger counterparts.”


Both Industry Index and Sovrn offer tools to check for errors in ads.txt files, and a quick Google search reveals a number of other tools in the open market. As demand partners really start to take action on bidding based on ads.txt files the tools on the market are likely to grow more robust.





Photo by Zany Jadraque on Unsplash