Ads.txt Publisher Guide


The Ads.txt initiative, backed by Google and the IAB, aims to reduce ad fraud. Publishers are encouraged to add this file to their websites, declaring who is authorized to sell programmatic ads for them. The absence of the ads.txt file or mistakes in its implementation will lead to significant ad revenue loss starting October 2017. 

Update: Ads.txt Google Chrome Extension

Fast and easy access to any website’s ads.txt file with a new and unique extension for Google Chrome, click here to learn more about the Ads.txt Extension.

Ads.txt Publisher Guide: Why, How and When Publishers Need to Add Ads.txt to their Websites

Ads.txt is an industry standard launched by IAB Techlab in May 2017. The goal of ads.txt is to deliver transparency in the programmatic advertising supply chain and crack down on:

  • Unauthorized reselling of ad inventory.
  • Domain spoofing.
  • Ad fraud.

Why Should Publishers Care about Ads.txt?

The main format of ad fraud is counterfeit inventory or creating online ad inventory pretending to be something that it is not. In part, counterfeit inventory consists of format misrepresentation, for example: presenting display banners as video. Yet the bigger part is domain misrepresentation, also known as domain spoofing.

When ad networks and SSPs sell ad inventory without the direct permission of the publisher, it has three immediate implications on the publisher:

  1. Loss of ad revenue – For every dollar the misrepresenting network earns could have been paid to the publisher.
  2. Brand reputation loss – Anyone pretending to be a brand is not limited by brand considerations and could harm reputation.
  3. Risk to the entire ecosystem – The big and growing part of ad fraud out of the ecosystem reduces return for advertisers, who lose faith and may accordingly withhold budgets.

Wrong Ads.txt? Immediate Loss of Ad Revenue

Starting October 2017, Google will not buy ad inventory from websites with wrong ads.txt attributes. This means that publishers who implement ads.txt incorrectly will not earn ad revenue from neither Google AdSense nor from DoubleClick AdExchange (Google Adx).

It is safe to assume that other members of the IAB will follow suite, including all leading SSPs and ad exchanges. Therefore, by early 2018, websites with wrong ads.txt implementation will suffer severe ad revenue loss.

Then, during 2018 things are going to get even worse. Google and other ad exchanges and DSPs will probably stop or significantly decrease ad buying from websites without the ads.txt file implemented.

What Happens to Websites without Ads.txt?

As described in the following inventory segments table, publishers should get their ads.txt implementation correctly.

Among the participating publishers, who implemented ads.txt in their website’s root, if the sell is unauthorized, Google and later on other demand sources will not buy any ads.

Currently, non participating publishers, who haven’t implemented ads.txt yet, will not be affected. But this would change soon and during 2018 more and more exchanges, including Google, will stop buying ads from websites with missing (or wrong) ads.text file.

In other words, for the long term, to guarantee that you continue to sell your ads, you must implement ads.txt correctly.

Clarification: Authorized inventory does not mean that the website is completely free of invalid traffic. Also, unauthorized inventory does not necessarily equal invalid traffic. Both are very good indicators of quality, but the ads.txt initiative does not solve all fraud issues. It still has room for growth and expansion, for example, verifying mobile apps and video ads.

What is Ads.txt: How it works?

On June 27th, 2017, the IAB announced the finalized ads.txt standard.
Ads.txt is a simple, flexible, and secure method for publishers and distributors to declare who is authorized to sell their inventory, improving transparency for programmatic buyers.
Importantly, the ads.txt project aims to prevent various types of counterfeit inventory across the ecosystem by improving transparency in the digital programmatic supply chain. You can read more about the project in the IAB Techlab website here.
Once implemented, Google and other participating ad exchanges will crawl websites and list who is authorized to sell programmatic ads on each website. If and when an unauthorized player will try selling ads, they will be able to decline. This will prevent fraudsters, arbitrage buyers and other grey-zone players to rig the system.

Ads.txt File Format and Example

Field #1: Domain Name of the Advertising System (Required)

The canonical domain name of the SSP, Exchange, Header Wrapper, etc system that bidders connect to. This may be the operational domain of the system, if that is different than the parent corporate domain, to facilitate WHOIS and reverse IP lookups to establish clear ownership of the delegate system. Ideally the SSP or Exchange publishes a document detailing what domain name to use.

Field #2: Publisher’s Account ID (Required)

The identifier associated with the seller or reseller account within the advertising system in field #1. This must contain the same value used in transactions (i.e. OpenRTB bid requests) in the field specified by the SSP/exchange. Typically, in OpenRTB, this is For OpenDirect it is typically the publisher’s organization ID.

Filed #3: Type of Account or Relationship (Required)

An enumeration of the type of account. A value of ‘DIRECT’ indicates that the Publisher (content owner) directly controls the account indicated in field #2 on the system in field #1. This tends to mean a direct business contract between the Publisher and the advertising system. Here you can find answer to the question how much do san diego movers cost? A value of ‘RESELLER’ indicates that the Publisher has authorized another entity to control the account indicated in field #2 and resell their ad space via the system in field #1. Other types may be added in the future. Note that this field should be treated as case insensitive when interpreting the data.

Field #4: Certification Authority (Optional)

An ID that uniquely identifies the advertising system within a certification authority (this ID maps to the entity listed in field #1). A current certification authority is the Trustworthy Accountability Group (aka TAG), and the TAGID would be included here.

For the full document with the ads.txt specifications, please visit the IAB Tachlab relevant page here.

Ads.txt File Example

Here is a simple example of the ads.txt file:

#Ads.txt example.cpm, pub-987654321234456, DIRECT, 1234567898776, RESELLER

Ads.txt Publisher Implementation Guide

Step #1: Create Text File

Create a text file with the parameters declaring who is authorized to sell your website’s inventory according to the format and example above.

Step #2: File Placement

Place the new text file at the root level of your domain, for example:

Step #3: Ads.txt Testing

After implementation, we recommend testing the ads.txt file to verify it is correct. Google offers a test tool within DFP (not yet available for all users). Another option is to contact Adnimation and we will be happy to help.

Ads.txt Download and Support

Google and Adnimation fully supports Ads.txt and we recommend that all publishers add the this text file to the root of the website (

You can download a sample file here: ads.txt download (right click and save, or visit

Here at Adnimation we help publishers increase ad revenue from programmatic ad sales, using technology together with a personal service. As part of our service, using our AdX Network Licence, we also offer publishers entry into Google’s AdX.

Advocating for the ads.txt initiative, we’re happy to help publishers with the implementation. If you have any question or would want us to test your file, please fill the details in the form here below. We will get back to you within 24 hours and would also tell you a little about our service.


Book a Discovery Call!

Learn how Adnimation can help improve your long-term growth

Our vision is simple: for creators to thrive doing what they love. That’s why we’re dedicated to helping you achieve lasting growth through innovative ad management and personalized support, allowing you to focus on what you do best — create amazing content.


Read More

Get Started Today

What would you like to monetize?

Join the Hundreds of Creators Who Trust Adnimation

As an experienced company with seasoned monetization experts, we blend advanced technology with human professionalism.

How does that manifest in reality? It means that our experts review the data on a daily basis, speak with advertisers and exchanges, and make improvements for publishers like you.

With us, you can soon be selling the same ad space for higher prices.