What is ads.txt?

The Interactive Advertising Bureau (IAB) released its first version of the Ads.txt Specification in June 2017. It's an initiative from IAB to increase the transparency in the ecosystem of programmatic advertising, aiming to eliminate unauthorized buying/selling transactions. The portion "ads" stands for "Authorized Digital Sellers."


For which inventories are ads.txt applicable?

The specification is only applicable for website inventories. Mobile apps or other non-web environments will be addressed in future IAB specifications.

What if ads.txt is not implemented?

If ads.txt is not implemented by publishers, it's assumed that anyone is authorized to resell the inventory.

How to implement ads.txt with Smaato exchange? 

  1. Location:
    Ads.txt should be placed under the root folder of the website's root domain (rather than subdomains), e.g.: http://www.example.com/ads.txt

  2. File format:

    1. A file can contain one or multiple entries, representing a different authorized seller. Each entry needs to be separated by line breaks.

    2. Each line can contain up to 4 fields, which are separated by commas. There can be spaces between each field. Definitions of each field are below:





      Field #1

      Required; domain name of the advertising system

      Fixed value: smaato.com

      Field #2

      Required; Publisher’s Account ID

      Publisher ID retrieved from SPX.

      Field #3

      Required; type of Account/ Relationship

      DIRECT if the publisher has a direct relationship with Smaato;

      RESELLER if the Smaato publisher ID belongs to a third party authorized to sell the publisher's traffic.

      Field #4

      Optional; Certification Authority ID

      Not adopted by Smaato at the moment.

      Sample value 1:


      Sample value 2: 

      smaato.com, 1001012346, RESELLER
    3. If a publisher has more than one publisher account (which we do not recommend), please ensure all publisher IDs are placed in the ads.txt file as different entries.  

    4. Comment lines are initialed by # symbols.

  3. Server response and configuration:
    1. Response code:
      1. Publisher server is supposed to return only HTTP 2xx status codes.

      2. HTTP 3xx status codes are currently not supported (which is in discussion and will be addressed in a future version of ads.txt).

    2. Expiration:
      Standard HTTP cache-control mechanisms can be used by both origin servers. If no cache-control directives are present, an expiry of 7 days is default.

    3. Seciruty:
      If traffic can come from both HTTP and HTTPS sites, please ensure that a copy of ads.txt is placed under both HTTP and HTTPS domains so that buyers can always access the file since HTTP 3xx codes are not supported.