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Ads.txt: Paving the road for a more transparent ecosystem

By Sandrine Tessier
Content Strategist
August 14th, 2017

Last May 2017, IAB rolled out a new initiative, Ads.txt (Authorized Digital Sellers), which is designed to combat some of the plagues of the programmatic landscape: on one side, domain spoofing and on the other, unauthorized reselling of inventory, also known as arbitrage.

What is Ads.txt?

Ads.txt stands for Authorized Digital Seller, which frankly, says it all: the initiative consists of a .txt file that lists all of a domain’s authorized sellers and is placed in the header code of a publisher’s website. The goal behind Ads.txt is quite simple: increase supply chain transparency in the programmatic ecosystem by providing a simple method for publishers to control their inventory and for buyers to have a clearer view of where they are buying from.

Why is it a good initiative?

district m’s mission statement is cored around being a trustworthy partner in programmatic solutions. As such, we want to support all initiatives that will contribute to making the programmatic landscape more transparent and profitable for all parties. Luc Marsolais, district m’s SVP of Business Operations, gives you the top 3 reason why the initiative is worth implementing:

  1. For buyers, it will offer better transparency of the inventory they are buying from. When bid requests are received, buyers can verify that the seller is authorized by the publisher, thus avoiding certain types of fraud like domain spoofing.

  2. For sellers, Ads.txt will help in preventing arbitrage and counterfeit impressions by limiting the number of buyers for unauthorized re-sellers. However, the success of the initiative relies solely on a unanimous adoption by the industry.

  3. In general, the initiative will enable journalists, bloggers, game designers and any other site owners to get their fair share from every impression and maximize their revenue by removing all intermediaries between them and the buyers.

“At district m we believe that accessing authorized inventory will benefit the entire ecosystem. This gives tools to publishers and advertisers to acknowledge supply path which reduces the amount of unwanted re-sellers. We are putting a lot of efforts into helping publishers implement ads.txt as quickly as possible since DSPs will beigin crawling sites and optimizing their bidding while making use of ads.txt data.”

How can you implement ads.txt and add district m as an authorized partner?

Step 1
If you don’t already have one, create a .txt file and name it “ads.txt”.

Step 2
Paste the required information in the file:

One line per authorized seller with up to four fields:

  • Domain name of the advertising system
  • Publisher’s account ID
  • Type of account/relationship (DIRECT or RESELLER)
  • Certification authority ID (currently TAG ID) – not mandatory

Here is an example of what it looks like:, 123, DIRECT, 456, RESELLER

Step 3
Add the ads.txt file in the root directory of your domain’s page – not in a subpage.

Step 4
To make sure you don’t miss out on any opportunities, we suggest that you add all your authorized sellers to the file for DSP crawlers to find. Any sellers not listed may be detected as an unauthorized seller by DSPs.

For all the specs pertaining to ads.txt, check out IAB’s full Ads.txt Specification Guide

If you need any help implementing ads.txt or need more information, reach out to our experts!

How can buyers access a publisher’s ads.txt file?

Buyers can check a publisher’s tags for an ads.txt file. For the file to be found, both the pub and the exchange representing it need to adopt the initiative. In the file, buyers should see the domain name of the advertising system, the publisher’s account ID, the type of relationship and sometimes, the Certification Authority ID.

For example:

Here’s what the file should look like:, 123, DIRECT, 456, RESELLER
exchangeone, 6Z8D7K, DIRECT
sellertwo, 2A4B6C, RESELLER

Again, the success of this initiative heavily relies on an en masse adoption by publishers – district m therefore strongly encourages all publishers to implement it. In the U.S., Ads.txt has already reached massive scale and is expected to be adopted by the majority of publishers by the end of 2017. With rising concerns over transparency of the programmatic ecosystem, district m believes ads.txt will bring the whole industry one step closer to making the programmatic landscape more trustworthy and beneficial for all parties.

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If you’re interested in learning more about how district m can help your business, please reach out to us!