Ads.Txt: Uncovering the Mystery Behind This Site Owner’s Must-Have

by Joost Nusselder | Updated on:  11/12/2022

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Are you a marketer looking to maximize your website’s earning potential? Then, ads.txt? is something that should be on your radar!

Ads.txt is an important tool for publishers and advertisers alike to help prevent fraud in programmatic advertising by verifying the authorized sellers of digital inventory.

In this blog post, we’ll explain what exactly ads.txt is, how it works and offer some best practices for optimizing your ads file.

What is ads txt

What is Ads.txt?

Ads.txt is a text file that helps publishers and advertisers manage their display ads relationships.

It allows publishers to declare who is authorized to sell their inventory, helping buyers avoid fraudulent activity and ensuring they are buying from legitimate sources.

What Does Ads.txt Do?

Ads.txt provides transparency in the digital advertising ecosystem by allowing publishers to publicly list all companies authorized to sell their inventory on open exchanges or other platforms such as SSPs (Supply Side Platforms).

This way, buyers can easily identify which sellers are allowed to represent a publisher’s inventory and make sure illegitimate actors in the space are not scamming them.

How Does Ads.txt Work?

Publishers create an ads.txt file with information about companies that have permission to sell their ad space on open exchanges or through SSPs, including details like account IDs and domain names for each seller listed in the file.

The ads.txt file must be hosted on the root domain of a website so it can be accessed by any buyer looking for it – usually via an automated crawler or bot – before making any purchases from third-party sellers associated with that site’s inventory pool.

Ads.txt offers many benefits to both publishers and buyers.

For publishers, it helps protect them from fraudsters attempting to purchase low-cost impressions without authorization.

Buyers will know which entities are authorized resellers for each publisher’s inventory before making any purchases.

Additionally, increased transparency is achieved as both parties understand where each impression originates within programmatic supply chains.

Ads.txt is an important tool for marketers to ensure the authenticity of their ad inventory and maximize revenue.

Next, we’ll discuss what ads.txt does and how it works to help you make the most out of your advertising campaigns.

Key Takeaway: Ads.txt is a text file that helps publishers and advertisers manage their programmatic advertising relationships, providing transparency in the digital advertising ecosystem. It allows publishers to declare who is authorized to sell their inventory, while buyers can easily identify which sellers are allowed to represent a publisher’s inventory.

What Problem Does Ads.txt Solve?

Ads.txt is a text file that helps publishers and advertisers identify authorized digital sellers of their inventory, preventing domain spoofing (a type of ad fraud) and arbitrage.

This fraudulent practice has been around for some time because it’s hard for advertisers to confirm the accuracy of information passed in bids.

Ads.txt makes this process easier by providing an open standard for identifying legitimate resellers of publisher inventory, making it harder for scammers to profit from illegitimate sites or hidden web browsers displaying ads without permission.

For marketers, ads.txt can help protect their brand reputation by ensuring that their ads are not appearing on unauthorized websites or pages with bot traffic or other shady practices like domain hijacking or arbitrage schemes.

It also allows them to control better where their campaigns appear and ensure they are getting the most out of every dollar spent on advertising since they know exactly who is selling their inventory online at any given time.

For niche websites, having an up-to-date ads.txt file ensures that all impressions sold through programmatic platforms are legitimate and have been purchased from authorized resellers only – eliminating any potential risks associated with buying from unknown sources which could lead to wasted ad spend due to low quality traffic or even worse – being blacklisted by major brands as a result of fraudulent activity taking place on your site!

Is Ads.txt Being Adopted by Publishers?

Ads.txt is a simple text file that publishers can upload to their web server, which contains the list of authorized digital sellers for their inventory.

The IAB Tech Lab created it to reduce fraud and increase transparency within AdTech.

Since its release in May 2017, many top publishers have adopted ads.txt, including Google, Facebook, AppNexus, and more.

However, adoption rates are still lower than expected, considering how easy it is to implement this solution into any website or app’s codebase.

According to reports from August 2018, only 20% of Alexa’s Top 1 Million sites had implemented ads.txt files on their websites; while this number has increased since then due to Google’s announcement that several of its AdTech platforms will start filtering for ads.txt files – adoption rates are still not where they should be at this point.

The reasons behind these low adoption rates vary with some publishers stating that although creating a text file and uploading it is easy enough – they still need to manually check the details with their partners before adding them onto the list; which can be time consuming depending on how many partners you work with as well as your internal processes when it comes down to verifying information accuracy etc..

Additionally, there could also be other factors, such as a lack of knowledge about what Ads.txt does or simply forgetting about updating or adding new entries onto existing lists due to busy schedules, etc.

In conclusion – even though Ads txt has been around for over 3 years now – adoption rates are still not where they should be yet; however, given recent announcements from major players like Google – we expect these numbers will continue increasing over time!

Is Ads.txt Mandatory?

Ads.txt is not mandatory, but it is highly recommended for marketers and niche websites.

Ads.txt stands for Authorized Digital Sellers and it is a simple text file that publishers can use to publicly declare the companies they authorize to sell their digital inventory (ads).

This file helps prevent fraud in programmatic advertising by ensuring that buyers only buy from authorized sellers.

The ads.txt file contains a list of all the authorized sellers who have permission to sell your ad inventory on open exchanges or through networks and agencies.

It also includes details such as seller domain name, publisher ID, account type, etc., which help identify each seller correctly, so buyers know where their ads will be served from and if they’re buying from an authorized source or not.

Having an ads.txt file in place ensures transparency between buyers and sellers while protecting both parties against fraudulent activities like domain spoofing or reselling unauthorized inventory at higher prices than what was originally agreed upon with the publisher or seller.

Additionally, it also helps ensure brand safety by making sure that advertisers don’t end up running their campaigns on sites with inappropriate content or ones known for click-fraud activities etc. since those won’t be listed as authorized sources in the ads.txt files of legitimate publishers and sellers anyway!

Overall, having an ads txt file can benefit both buyers and sellers alike by providing more security when transacting online as well as helping build trust between them over time – something which should always be prioritized especially when dealing with large sums of money!

How to Implement Ads.txt

Creating an Ads.txt File: The first step to implementing Ads.txt is creating the file itself.

This text file should contain all of the authorized sellers that you want to include in your programmatic advertising setup, as well as any additional information needed for each seller such as their domain name and account ID.

Make sure to format this correctly according to the IAB Tech Lab’s specifications so that it can be read by ad exchanges and other platforms properly.

Adding the File to Your Website

Once you have created your Ads.txt file, you need to add it onto your website in order for it to be accessible by ad exchanges and other platforms.

To do this, simply upload the file into a directory on your site’s root domain (e.g., www.examplewebsite/ads/ads_text).

It is important that you use a secure connection when uploading files like these so make sure SSL encryption is enabled on your server before proceeding with this step!

After adding your Ads.txt file onto your website, it is time to verify that everything has been set up correctly and that all of the entries are being read properly by ad exchanges and other platforms.

To do this, use a tool like Google Ad Manager or AppNexus’ ads txt validator which will scan through each entry in detail and provide feedback if there are any errors or issues with formatting or syntax within them.

Additionally, some publishers may also offer their own verification tools so check with them directly if they do not appear in either of these two services mentioned above.

I use Ezoic as an Adsense alternative and they do this for you.

Ads.txt is a text file that helps publishers and advertisers to ensure the authenticity of their ads.

It allows them to list all authorized sellers for their digital inventory, so they can be sure that only legitimate sources are buying ad space on their website or app.

Implementing Ads.txt requires creating a text file with the correct syntax, adding it to your website, and verifying that it is working properly.

Creating an Ads.txt File

To create an Ads.txt file you will need to use plain text format (.TXT) and include specific information about each authorized seller in separate lines following this format: “domain name”, “publisher ID”, “type of account” (DIRECT or RESELLER).

For example: “”, “123456789”, DIRECT

Adding the File to Your Website

Once you have created your Ads.txt file you must add it to your root domain directory so that it can be accessed by anyone who visits your site or app URL followed by /ads.txt (e.g., www(dot)yoursite(dot)com/ads(dot)txt).

This will allow buyers and other third-party vendors access the list of authorized sellers associated with your domain name when they search for available inventory on exchanges like Google Ad Manager or AppNexus Marketplace etc.

Verifying your Ads.txt file is working properly

After uploading your Ads.txt file onto your website’s root directory, you should verify its accuracy using online tools such as IAB Tech Lab’s Validator Tool which checks if there are any errors in formatting as well as whether all entries match up correctly with what was entered into the original text document before being uploaded onto the server hosting provider’s system.

Additionally, you should also check periodically for updates from time to time since new vendors may have been added over time which could affect how buyers view available inventories associated with your site.

Ads.txt is an important tool for marketers to ensure they are working with legitimate ad networks and that their ads are being displayed properly.

Key Takeaway: Creating an Ads.txt file is the first step to implementing programmatic advertising, and it’s important to make sure that it is formatted correctly according to IAB Tech Lab’s specifications. Once created, you need to add the file onto your website in a secure directory so that ad exchanges can read it properly.

Common Mistakes When Implementing Ads.txt

When implementing Ads.txt, it is important to be aware of the common mistakes that can occur to ensure your file is working properly. One mistake to avoid is incorrectly formatted files.

The syntax for an Ads.txt file must be exact, and any small error could cause issues with your ads being served correctly.

Make sure you double-check all entries for accuracy before uploading the file onto your website!

Another mistake when implementing Ads.txt is using the wrong domain name in the entries of your file.

If you are using a subdomain or vanity URL, make sure these are reflected accurately in each entry so that buyers can find and access them without issue.

Finally, it is essential not to forget about updating your Ads.txt regularly. New sellers may have been added since the last update or existing ones may have changed their domains or policies.

If this information is not up-to-date, buyers will not be able to access those ads properly either.

To keep everything running smoothly, check back every few weeks and update accordingly whenever necessary so that all authorized sellers are included in your list at all times.

Implementing Ads.txt correctly is essential to ensure that trusted sources serve your ads, so be sure to avoid these common mistakes and keep your file updated regularly for optimal results.

Next, let’s look at the benefits of using Ads.txt on your website.

Best Practices for Optimizing Your Ads.txt File

It’s an important tool for marketers and advertisers, as it helps ensure that all programmatic advertising transactions are legitimate and secure.

To get the most out of your Ads.txt file, there are several best practices you should follow:

Organize Your Entries Alphabetically

When adding entries to your Ads.txt file, make sure they’re organized alphabetically by domain name or publisher ID so they can be easily found and verified by buyers.

This will help ensure accuracy when buying from multiple sources at once.

Include All Authorized Sellers

Make sure all authorized sellers are included in your Ads.txt file; otherwise, buyers may not be able to purchase inventory from them if they don’t appear on the list of approved vendors in the Ads.txt file itself!

Check for Updates Regularly

As new vendors come onto the scene or existing ones change their policies, it’s important to regularly check for updates in order to keep up with any changes made within the industry – this will help protect both buyers and sellers alike!

By following these best practices when optimizing your Ads.txt files, you can be sure that all programmatic advertising transactions are conducted securely and legitimately, leading to better results overall.

Troubleshooting Tips for Fixing Issues with Your Ads.txt File

If you’re having trouble with your Ads.txt file, there are a few troubleshooting tips that can help get things back on track. First, check for syntax errors in the file.

Make sure all entries are properly formatted and that no typos have been made.

If an entry is incorrectly formatted or contains a typo, it won’t be recognized by the system and will need to be corrected before it can work properly.

Next, ensure you have included all authorized sellers in your Ads.txt file.

This includes any third-party networks or exchanges you may be working with as well as direct deals with advertisers or publishers who are buying ads from you directly.

Not including these parties could lead to lost revenue opportunities so make sure they’re listed correctly in your Ads.txt file!

Finally, ensure that the correct domain name is used when setting up your Ads.txt file.

This is important as any ad requests sent to an incorrect domain will not be able to find the right Ads.txt information and thus will not display correctly on your website.

Double check everything before submitting it to guarantee accuracy and currency of data.

By following these troubleshooting tips, you can ensure that your ads.txt file is properly set up and running smoothly.

Next, let’s look at how to optimize the performance of your ads.txt file for maximum revenue potential.

Apps-Ads.Txt for Mobile Apps

App-ads.txt is a new initiative from the IAB Tech Lab that helps marketers protect their mobile app inventory from fraud and unauthorized reselling.

It works in much the same way as ads.txt, which was introduced to help protect web domains, by providing an additional layer of security for advertisers buying ad space on mobile apps.

The app-ads.txt file is uploaded to the root directory of your website and contains information about authorized sellers who are allowed to sell your app’s inventory through programmatic channels such as Google Ad Manager or AdMob.

This allows you to block any unauthorized sellers who may be trying to resell your inventory without permission, thus protecting you from fraudulent activity and ensuring that only legitimate buyers have access to it.

It also provides more transparency for buyers so they can easily identify where their ads will appear before making a purchase decision, reducing the risk of them unknowingly buying counterfeit or low quality traffic sources that could damage their brand reputation or waste their budget on ineffective campaigns.

In addition, using app-ads.txt gives publishers greater control over how they monetize their content since they can now specify exactly which companies are allowed to buy ad space on their apps and set limits on how much each one can spend per dayweekmonth etc., helping them maximize revenue while minimizing potential losses due to fraudsters attempting to take advantage of unsuspecting buyers with fake inventories or click farms generating bogus impressions & clicks at inflated prices

FAQs about Ads.Txt

What is ads TXT used for?

Ads TXT is a text file used to declare the relationships between publishers and advertising technology companies. It allows publishers to publicly disclose their authorized digital sellers, helping buyers verify who they are buying ads from. Ads TXT helps ensure that ad inventory is being purchased through legitimate channels and not from unauthorized sources. This improves transparency in the programmatic ad ecosystem, allowing buyers to trust that they are getting what they paid for.

What’s in an ADS txt file?

An ADS.txt file is a text-based file that allows publishers to declare who is authorized to sell their digital inventory. It helps advertisers and other third parties verify the authenticity of the publisher’s inventory, protecting them from fraud. The file contains information such as seller account ID, domain name, and type of relationship with the publisher (direct or reseller). This ensures that buyers are buying from legitimate sources and not from unauthorized sellers.

Where is ads txt file?

The ads.txt file is a text file that resides in the root directory of a website and contains information about who is authorized to sell advertising on that site. It was created by the Interactive Advertising Bureau (IAB) as an effort to combat fraud in programmatic advertising, and it helps marketers ensure they are buying from legitimate sources. The ads.txt file should be updated regularly with any changes to authorized sellers, so marketers can have confidence when purchasing inventory for their campaigns.


Ads.txt is an important tool for marketers to use when optimizing their websites and campaigns.

By understanding what it is, how to implement it, common mistakes made when implementing it, best practices for optimizing your ads.txt file, and troubleshooting tips for fixing issues with your ads.txt file, you can ensure that you are taking advantage of all the benefits this powerful tool has to offer!

So don’t forget about ads.txt? – it’s a great way to maximize your website’s potential!

Joost Nusselder is The Content Decoder, a content marketer, dad and loves trying out new tools en tactics. He's been working on a portfolio of niche sites since 2010. Now since 2016 he creates in-depth blog articles together with his team to help loyal readers earn from their own succesful sites.