Saturday, January 14, 2023

IAB Tech Lab Adds Ads.Txt Values To Help Buyers Determine The Owner And Manager Of Inventory

New York, NY (April 13, 2022) – Today, IAB Tech Lab, the digital advertising technical standards-setting body, announced an update to the widely adopted ads.txt specification which they have opened for public comment for 60 days.

The update includes two new values for publishers to declare within their ads.txt files, “ownerdomain” and “managerdomain” which helps  increase the transparency into seller relationships via sellers.json and further strengthens ads.txt as a tool to reduce fraud in buying and selling of advertisements on websites, mobile apps and connected TV.

The “ownerdomain” value is used to specify the domain of the business that owns the website that the ad is being served on. This helps to connect the seller domain for PUBLISHER entries in sellers.json files, which has previously been hard to programmatically validate resulting in mismatched seller domains, especially when an entity owns multiple publisher properties.

“Owner domain provides a critical link between the business entity being paid, and listed in a sellers.json file and the ads.txt file on the site being monetized. Publicly connecting these dots closes a potential gap that allows for misrepresentation,” said Neal Richter, Chairman of the Board of Directors, IAB Tech Lab.

The “managerdomain” enables the publisher to declare the primary or exclusive monetization partner of that sites inventory. This new addition to ads.txt will help to level the supply path optimization (SPO) playing field for small to medium publishers. This is because publishers that outsource yield management, and transact under their manager’s seller ids are automatically made to appear as though they have multiple hops to access their inventory; this is a challenge when supply path optimization’s focus on buying from the fewest number of hops in the supply chain to access inventory. The addition of the Manager Domain in ads.txt will helps buyers know that even with multiple hops, this may be the most optimal route to access that publisher’s inventory.

Paul Bannister, Chief Strategy Officer of CafeMedia said, “We are excited to use the manager domain field with our publishers to give buyers more clarity that buying a given publisher through us is the most optimal path to buy that inventory. While our entries have always been in the publisher’s ads.txt file, the manager domain value provides an unambiguous link between our sellers.json entry in exchange’s sellers.json files and the publisher’s ads.txt file, providing buyers with a clear understanding of supply path.”

“Overall these two new values help to bring more transparency to the supply chain by enabling advertisers to better identify and control who their spend is going to,'” Said Shailley Singh, Vice President of Product, IAB Tech Lab. “This helps to further combat fraud, minimize the loss of revenue for advertisers, and helps to ensure spend is being directed to the right places, all of which is essential for the sustainability of our industry.”

The public comment period for ads.txt 1.1 will run through May 31, 2022, after which the IAB Programmatic Supply Chain Working Group Ads.txt Subgroup, which developed the tool, will evaluate the comments received. It will then make any necessary revisions, and release a final version. 

About IAB Technology Laboratory

Established in 2014, the IAB Technology Laboratory (Tech Lab) is a non-profit consortium that engages a member community globally to develop foundational technology and standards that enable growth and trust in the digital media ecosystem. Comprised of digital publishers, ad technology firms, agencies, marketers, and other member companies, IAB Tech Lab focuses on solutions for brand safety and ad fraud; identity, data, and consumer privacy; ad experiences and measurement; and programmatic effectiveness. Its work includes the OpenRTB real-time bidding protocol, ads.txt anti-fraud specification, Open Measurement SDK for viewability and verification, VAST video specification, and Project Rearc initiative for privacy-centric addressability. 

File format

The IAB's ads.txt specification dictates the formatting of ads.txt files, which can contain three types of record; data records, variables and comments. An ads.txt file can include any number of records, each placed on their own line.

Since the ads.txt file format must be adhered to, a range of validation, management and collaboration tools have become available to help ensure ads.txt files are created correctly.

Latest specification v1.0.2 recommends using a placeholder record to indicate the intent of an empty ads.txt file:, placeholder, DIRECT, placeholder

State of adoption

By November 2017, more than 44% of publishers had ads.txt files. More than 90,000 sites were using ads.txt, up from 3,500 in September 2017, according to Pixalate. Among the top 1,000 sites that sold programmatic ads, 57 percent had ads.txt files, compared to 16 percent in September, per Pixalate.

Latest adoption data per's Ads.txt Industry Dashboard:

Websites TierJan 30th, 2020Jan 30th, 2019Jan 30th, 2018
Alexa Top 1,00044.20%40.90%33.70%
Alexa Top 5,00039.58%36.00%29.06%
Alexa Top 10,00036.66%32.75%25.18%
Alexa Top 30,00031.71%26.34%18.52%

Google has been an active proponent of ads.txt and pushing for faster, widespread adoption by publishers. From the end of October 2017 Google Display & Video 360 only buys inventory from sources identified as authorized sellers in a publisher’s ads.txt file, when a file is available. ads.txt may become a requirement for Display & Video 360.


ads.txt (Authorized Digital Sellers) is an initiative from IAB Technology Laboratory. It specifies a text file that companies can host on their web servers, listing the other companies authorized to sell their products or services. This is designed to allow online buyers to check the validity of the sellers from whom they buy, for the purposes of internet fraud prevention.