Ads.txt was introduced by the Interactive Advertising Bureau (IAB) in 2017 as a security provider for the programmatic advertising ecosystem. It significantly increased the transparency in the field, as due to it publishers and buyers can verify inventory-authorized sellers in the industry.

Ads.txt is a publicly available record of authorized digital sellers for the publisher’s inventory that programmatic buyers index and reference to ensure they are purchasing from an authorized seller. 

The success of the protected purchases requires two-sided contributions both from publishers and buyers. 

Firstly, participating publishers should adopt the tool and publish the authorized sellers’ list in their domain. An example is 

Further, if the programmatic buyer wants to make a purchase, they will crawl the web and access the publisher’s ads.txt file. Buyers can identify the authorized sellers by comparing their ads.txt with the OpenRTB data.

The main beneficiaries of the ads.txt are:

  • Domain owners who sell inventory on exchanges through their accounts.
  • Intermediary networks and sales houses who sell inventory on behalf of domain owners.
  • Content syndication partnerships, where several authorized sellers offer the same inventory to buyers.

In other words, ads.txt helps each participant of the ad’s inventory secure their portion of ownership and income. 


The necessity of ads.txt

The media buying process faces increasing demand. As a result, more and more inventory suppliers enter the market. Often, publishers lose the potential of monetizing their actual inventory. This happens because fraudsters sell mislabelled ad space and fake traffic under the publisher’s name. On the other hand, buyers waste advertising budgets by paying unauthorized sellers, who provide them with fake, non-human traffic. 

Fraudsters succeed to mislead buyers because the latter usually rely on the legitimate transition of their purchased URLs by publishers. However, there is no ultimate way to confirm that the passed URLs represent the actual impression moving across exchanges. Also, buyers are not able to identify who is selling those impressions. 

Even though the URL and Publisher ID are included in the impression from the Open RTB protocol, buyers still can’t identify the publisher ID owner. The mentioned issue, along with the problem of validating the information sent in the RTB bid request, leaves space for counterfeit inventory. Ads.txt addresses this popular phenomenon of the inventory selling process.

Counterfeit inventory is sourced from an original domain, deliberately mislabeled, and offered for sale under a different domain. That’s a profitable “business” for domain fakers as they actually sell nothing under the real publisher’s highly-valued name. 

While the programmatic buyers think they are buying a golden place in the media, which generates good traffic, neither the media inventory nor the traffic is real. 

That’s the necessity behind the ads.txt format. It’s an official and direct communication between publishers and buyers, which excludes intermediary fraudsters. 

Tips: How to use ads.txt for your website

The process of uploading ads.txt is quick and straightforward. It’s similar to robots.txt file installing, which appears in the majority of websites. Also, there are no restrictions on which websites can have the ads.txt. The most important here is that the information is accurate and includes the necessary details. 

The image below shows the data about the inventory authorized sellers, that should be included in the ads.txt list.

Mandatory sections:

  • Partner1 is the domain name of the authorized seller or reseller of the publisher. 
  • 678910 is the seller or reseller account ID. You can get it directly from the seller. 
  • DIRECT or RESELLER indicate the type of relationship between a publisher and a seller/reseller. Direct relationship means publishers cooperate with the vendor without intermediary parties. Reseller relationship includes intermediary vendors.

Optional sections:

  • g45tg4e is the certification authority ID or the unique identification code of the advertising system.
  • #banner shows what kind of inventory the publisher sells.

As you see, the ads.txt file includes all the first-importance information about the publisher. This means that if the programmatic buyer receives an offer bid, they can validate the seller information. Particularly, they can crawl the publisher’s ads.txt to see whether the reseller is included in the list and compare the data.

Therefore, if all the websites have an accurate list of their vendor partners, and all the buyers check the list before making a purchase, fraudsters have no chances.

How to add ads.txt to your website?

  1. Use a simple text editor

The process of adding an ads.txt with the text editor is similar to that of any other document. For that, follow the basic rules.

  • create the text
  • input the above-required data in the mentioned order
  • save it in .txt format
  • upload it to your website as a new page at 
  1. Use WordPress plugins

Install an ads.txt plugin on your WordPress-managed site. After installing, click Settings > Ads.txt on the left panel. Place the required data and press Save

  1. Without plugins in WordPress

On the left panel, select Media > Add new > [ Add the file, strictly naming it ads.txt ]> Save. 

  1. Use Google AdSense

In your AdSense account, click on Sites, then press the Down arrow, choose Create an ads.txt file for, and then Download. After these steps, your ads.txt will be downloaded automatically. You can further upload it to the site’s root directory. 

  1. Use Google Ad Manager

In your Google Ad Manager account, select Admin > Ads.txt management> Web ads.txt > Create an ads.txt file > publish ads.txt to root domain.

After those steps, you will have your vendors list generated by Google Ad Manager. Edit it if needed and copy/paste the list to your created ads.txt. You can also download it and upload it to the root directory later. 

  1. Let Adnimation do it for you

Publishers who partner with Adnimation for managing their ad sales process enjoy remote management of their ads.txt file. This service is a part of the technology and monetization service. This way, the publisher need not worry about keeping the file up to date and it’s always accurate. 

What to avoid?

Before listing the main things to avoid creating the file, keep in mind that you create the list for the web crawler robots. This means the list should be easily accessible for the robots. Otherwise, its main mission to secure your inventory sales can’t be completed. 

Simpler: robots should be able to read the information to verify it. 

Read the main mistakes which can result in poor ads.txt performance below. 

1. The ads.txt of the website became a meme because it used to contain more than 24,000 rows. That’s not the best idea because Demand Side Platforms read and consider 200-300 of the rows in the best case. For the worst case, DSPs will simply ignore your list.

If there are too many vendors, it’s better to include only the main ones in the list. 

2.’s ads.txt used to have more than 3,200 resellers with 118 unique partners. If your ads.txt is like this, it’s better to change it. DSPs are pretty suspicious about second-level selling partners. 

3. Keep a good syntax: avoid typos and keep all the information in one line. The good syntax is the usual structure of the ads.txt robots are “taught” to identify. If they see the same vendor’s information broken in 2,3, or more rows, your time and effort to construct a list will be lost. 

Ads.txt is not ideal

Even though ads.txt is modern security must-have for advertisers and purchases, it’s not flawless. 

First of all, the success of the ads.txt format depends on each industry player. So, to have real results from it, all the publishers should adopt the list and regularly update it. Otherwise, advertisers will not have an opportunity to identify the authorized and trustful resellers for all publishers. 

Besides, the impact of manual errors is crucial for the DSPs review of the list. On the other side, the manual error probability is high because there are intensive changes in a big number of seller and reseller partners. 

However, there is good news. IAB is continuously working on its products. As a result, the ads.txt’s popularity is rising and more industry players engage with it. 

Lastly, for media professionals, we recommend adding the Chrome extension Ads.txt Analyzer, which provides easy access to any website’s ads.txt file directly from the browser. It is available for installation here

In the next articles we will review the application of ads.txt not only to websites but also to mobile apps and even Connected TV (CTV).


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