The Steps Publishers have to Undertake Deploying ‘/ads.txt’ files

Description: This is a guide for publishers describing how to work with their advertising systems based on ‘/ads.txt’ files.


The digital advertising market is one of the most profitable environments, especially for bad actors and the last year biggest hot-button issue is domain spoofing with the one of the most impressive cases in the industry, – the Methbot.

Addressing such cases, the IAB Tech Lab has introduced the Ads.txt initiative encouraging publishers to publish an ‘/ads.txt’ file on their websites. Ads.txt is an uploaded to a publisher’s website simple .txt file that lists all authorized digital sellers of a publisher web inventory. Deploying a reference crawler written by the IAB OpenRTB Working Group buyers can find these lists at and match with the inventory they’re buying against the listed.


The adoption of ads.txt has been slow but continuously progressing and that’s promising. As Ad Ops Insider reports almost 13% from the Alexa 10K global domains have deployed ‘/ads.txt’ files on their domains. The recent scandal with the Financial Times video ad inventory sold on numerous exchanges despite the fact that FT didn’t sell it programmatically, should even hasten the adoption process.

However, why you as a publisher have to adopt it? First and foremost, to secure yourself against bad actors selling your web inventory without authorization and stilling the money you could actually own as a domain owner.

Publishers should also keep in mind that buyers will no longer be buying ad impressions from unauthorized resellers by Q1, 2018. On the other hand, Google’s DoubleClick Bid Manager (DBM) announced that by the end of October they will stop buying inventory from sources not identified as authorized sellers in publishers’ ads.txt files. To sum up ads.txt will become a requirement for those willing to work with DBM.


‘/ads.txt’ file syntax definition with reference to the Ads.txt Specification version 1.0.1

According to the latest Ads.txt Specification version 1.0.1 released by the IAB Tech Lab in September, 2017 all data in ‘/ads.txt’ file should be ‘text/plain’ and comprising the following information:

  • Domain name of the advertising system (Required)
  • Publisher’s Account ID (Required)
  • Type of Account/ Relationship (Required)
  • TAG Certification Authority ID (Optional)

An ‘/ads.txt’ file officially supports several variable fields, such as:

  • Contact information (Optional)
  • Subdomain (Optional)

Creating an ‘/ads.txt’ file manually

Implementing ads.txt is easy and doesn’t require much efforts. Everything a publisher has to do is to post the ‘/ads.txt’ file in a domains’ root folder, listing in it all authorized resellers (exchanges and/or SSPs) he/she works with as shown below:

Example of ads.txt file on Businessinsider Website

However, it may become very time consuming gathering all the sellers and resellers names and sometimes even impossible to accomplish manually, as you don’t usually see the full list of your inventory resellers.

Creating an ‘/ads.txt’ file with the ads.txt Generator

With the aim to simplify the process of ads.txt generating and include the full list of the resellers you work with we have created a free of charge and easy to use Ads.txt Generator. It can be used both for creating a new ‘/ads.txt’ file and updating an existing already file.

  • Creating a new “/ads.txt” file with the ads.txt Generator

All it takes is entering your domain name on the ads.txt Generator Page and pressing the button “Generate” afterwards you will receive a full list of ‘direct’ advertising systems and ‘resellers’ based on up to ten of your web site pages.

  • Updating an existing “/ads.txt” file with ads.txt Generator

To update the “/ads.txt” file you have to complete the same steps as when creating a new file. Again, you enter your domain name on the ads.txt Generator Page and press the button “Generate”. The system will identify the “/ads.txt” file automatically and update it based on the data available on your web site.

Both times, you will receive a file comprising of the three required fields (Advertising System, Seller Account ID, Type of Account/Relationship) and the four optional fields (Certification Authority ID, #Comments, Contact, Subdomain).  

What if you’d like to add to the ‘/ads.txt’ file your Subdomains?

As you may have noticed, the IAB Tech Lab Spec 1.0.1 in the Paragraph 4.5  added recommendations regarding the process of subdomains crawling. According to the updates, if you work with a different set of authorized systems on a subdomain, you may list it as well and the crawler will take the subdomain as an independent URL.

What if your ‘/ads.txt’ file identified the unauthorized resellers of your web inventory?

When you are all set having a full list of your direct partners and resellers you may find out that there is an exchange “N” which is selling your inventory as well though it’s never been authorized by you. What are your next steps?

First, you can reach out to the exchange directly asking to remove your inventory from selling. The bad news, is that the exchange may not respond to your request. If so, you can contact the DSP or Agency to stop buying your inventory from the certain exchange as it is fraudulent. If this doesn’t help, contact us [link to contact form] and we will speak up for you disclosing the bad actors [link to the blog!]


Too long the digital market has been a profitable space for fraudsters who have been stealing money from both buyers and sellers. The IAB Tech Lab Ads.txt initiative is a great step towards creating a healthy advertising ecosystem and now, only publishers can distinguish how things unfold by either proactively adopting the solution or ignoring it. We encourage you to make the right decision and start receiving the revenues you deserve! To make this process smooth and easy you can use the Ads.txt Generator without any charges! Let’s clean up the environment we live in together!