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Ad Fraud

What is Ads.txt? Everything You Need to Know

What is ads.txt? It’s a file standard created by IAB to help buyers verify whether or not the ad inventory they are purchasing is authentic. Learn more.

Are you tired of the ad fraud that’s eating away at your revenue? Want to ensure that your ad inventory is only sold by authorized sellers? Look no further than Ads.txt. Wondering what is ads.txt? Don’t worry, we’ve got you covered.

It’s a game-changing solution for publishers looking to protect their inventory from unauthorized sellers and increase their revenue. By keeping an up-to-date Ads.txt file on their website, publishers can take control of their online advertising and safeguard their revenue.

In fact, “The Interactive Advertising Bureau (IAB) is also demonstrating its commitment to transparency and reducing fraud in the advertising industry by releasing an updated version of the ads.txt standard, version 1.1.

This latest update highlights the IAB’s serious approach to utilizing the ads.txt file as a crucial tool in promoting a trustworthy and secure advertising ecosystem.

Let’s dive into the details of what is ads.txt and how it can benefit the digital advertising industry by promoting transparency and reducing fraud

What is Ads.txt?

Ads.txt (Authorized Digital Sellers) is a simple, flexible, and secure way for publishers to declare the companies authorized to sell their digital inventory. It is an IAB-initiated text file that lists all of the authorized digital sellers for a website.

Some key points of Ads.txt are:

  • It helps to reduce ad fraud by verifying the legitimacy of ad inventory.
  • It allows advertisers to buy inventory with confidence and eliminates the risk of buying counterfeit inventory.
  • The file is stored on the publisher’s website and is accessible to anyone, making it easy for ad buyers to verify the legitimacy of the inventory.
  • It is a simple, open-source solution that requires no specialized software or tools.
  • Its adoption is highly encouraged by the advertising industry to increase transparency and reduce fraud in the programmatic advertising ecosystem.

How Does Ads.txt Work?

Ads.txt by allowing publishers to list their authorized digital sellers in a text file hosted on their domain. Here is how it works:

Image Source – IAB Tech Lab

1. File Creation

  • Publishers create a publicly accessible file on their website that lists all of the authorized digital sellers for their inventory.

    The file specifies the relationship between the publisher and the ad exchanges, supply-side platforms (SSPs), and other entities that are authorized to sell the publisher’s inventory.

2. Verification by Advertisers

  • When an advertiser wants to purchase ad space on a website, they can check the publisher’s Ads.txt file to confirm that the seller is authorized to sell the inventory.
  • If the seller is not listed in the file, the advertiser can assume that the inventory is counterfeit and avoid purchasing it.

3. Updating the File

  • The Ads.txt file is updated regularly to ensure that it remains current and accurate. This helps to reduce the risk of fraud in the programmatic advertising ecosystem.

By utilizing a simple text file format that is easy to implement and maintain, ads.txt makes it accessible to all types of publishers, regardless of their technical expertise.

Now that you have understood what is ads.txt and how it works, let’s have a look at how buyers can verify the same.

How Do Buyers Verify Ads.txt Inventory?

There are a few ways to do this. If both the publisher and exchange have adopted ads.txt, buyers can check the ad tags to make sure that they have a legitimate connection.

Buyers can also go to the publisher’s website, pull the ads.txt file and manually check if the exchange that they are working with is listed.

IAB has also launched a crawler that can quickly query publisher websites for the ads.txt file, this is great for buyers who need to quickly verify multiple publishers.

Importance of Updating Ads.txt Files Regularly?

Ad Fraud Prevention

Keeping the file up to date ensures that only authorized sellers can sell inventory on your domain, which helps prevent ad fraud.

Though Ad.txt can be a useful tool in the effort to prevent ad fraud, it’s not a comprehensive solution and should be used in conjunction with other ad fraud prevention measures.

Improved Ad Revenue

By only allowing authorized sellers to sell inventory on your domain, you can ensure that you are getting the highest possible ad revenue.

Better Advertisers Trust

By keeping your ads.txt file up to date, you can demonstrate to advertisers that you take ad fraud prevention seriously, which can help build trust and increase demand for ad space on your domain.

Also Read – How to Create, Update, and Implement ads.txt in WordPress

Best Practices for Keeping Ads.Txt files in Check

1. Verify the List of Authorized Sellers

Regularly check the list of authorized sellers in your ads.txt file to ensure that it is accurate and up to date. Remove any sellers that are no longer authorized to sell inventory on your domain.

2. Monitor Unauthorized Sellers

Use tools and services to monitor for unauthorized sellers that may be attempting to sell inventory on your domain. If you find any, take immediate action to remove them from your ads.txt file.

3. Keep the Ads.txt File Updated

Regularly update your file to reflect any changes in your authorized seller’s list, such as the addition of new sellers or the removal of old ones. This will ensure that your file remains accurate and effective in preventing ad fraud.

Ads.txt file
Here’s how it looks like
Courtesy – AerServ

Also Read – Visually Manage Your Ads.txt Files

We hope that by now you are well-versed in all the nitty-gritty of ads.txt. That being said, let’s take a look at what is app-ads.txt.

What is Ads.txt for Mobile Apps?

Ads.txt for mobile apps is known as app-ads.txt, and more and more app developers are starting to adopt it. Now you must be wondering why it exists and it has been built differently. Here’s why:

Image Source – Human Security

Ads.txt for mobile apps refers to a file that lists the authorized domain sellers for in-app advertising. This helps to combat ad fraud by ensuring that only approved and legitimate sellers are serving ads in a particular mobile app.

However, the implementation of ads.txt in mobile apps faces challenges due to the absence of a standardized location to store the file, unlike in the case of websites where it can be stored on the website’s domain.

Ads.txt in mobile apps lacks a straightforward method for storing a list of authorized domain sellers. Unlike websites, mobile apps do not have a dedicated web domain where the ads.txt file can be hosted. Thus, app-ads.txt comes into the picture.

Adoption of App-ads.txt

Approximately 32.31% of all apps available on Google Play have implemented “App-Ads.txt”, totaling 1,224,225 out of the overall 3,788,640 apps on the platform.

Image Source – 42 Matters

The estimations by 42 matters also present the widespread adoption rate of app-ads.txt files by Google’s Play Store’s top 1000 apps.

Image Source – 42 Matters

A higher percentage of the top 1,000 apps on Google Play have adopted “App-Ads.txt” with a rate of 72.1%. This means that 721 out of the top 1,000 apps have implemented the standard.

This highlights a greater adoption rate among top-performing apps compared to the overall app population on Google Play

Benefits of Implementing App-ads.txt

Ad Fraud

The app-ads.txt file helps to prevent ad fraud by ensuring that only authorized sellers are allowed to sell and serve advertisements on a particular app.

This helps to prevent unauthorized parties from exploiting the app to serve fake or low-quality advertisements.

Improved Transparency

The app-ads.txt file provides transparency in the digital advertising ecosystem by making it easier to identify authorized sellers. This helps to improve the overall quality of advertisements and reduces the chances of ads being served by fraudulent or unauthorized parties.

Increased Confidence

By verifying that advertisements are served by authorized sellers, app-ads.txt helps to increase the confidence of advertisers, app publishers, and users in the digital advertising ecosystem. This helps to build trust and foster a more secure and reliable digital advertising environment.


In conclusion, both Ads.txt and app-ads.txt are a simple yet powerful tool that plays a crucial role in the digital advertising industry.

By providing a clear and authoritative list of authorized digital sellers, it helps to prevent ad fraud, increase transparency, and improve the overall quality of advertisements.

Its ease of implementation and widespread adoption make it an effective solution for promoting a more secure and trustworthy digital advertising environment.

Moreover, it also recommended to publishers keep themselves updated with the IAB ads.txt updates. Publishers will be required to update their ads.txt files to align with the new changes and maintain compliance.

Whether you are an app publisher, website owner, or advertiser, implementing Ads.txt is a vital step in ensuring a safe and successful programmatic advertising experience.


1. What is ads.txt used for?

An IAB Tech Lab initiative, authorized digital sellers, or ads.txt, helps to ensure that your digital ad inventory is only sold by authorized sellers (such as AdSense).

2. Is ads.txt mandatory?

It is not mandatory to use ads.txt, but it is strongly recommended. This can prevent counterfeit inventory from being mislabeled as coming from a specific domain, app, or video.

3. How long does an ad.txt take?

AdSense may take up to 24 hours to process your updated ads.txt files. Our Help Center provides more information about ads.txt, how buyers will use it, and how to implement it.

4. Who uses ads.txt?

Ad.txt files are used by a variety of parties in the digital advertising ecosystem, including:
Ad Exchanges
Ad Networks and Demand-Side Platforms (DSPs)
Ad Verification and Brand Safety Companies

5. Where is my app-ads txt file?

Your app-ads.txt file is hosted on your app’s domain and can be accessed by adding “/app-ads.txt” to the end of your app’s URL. The file should contain a list of authorized digital sellers for your app, separated by line breaks.