Adstxter is a lightweight tool designed to help you check your sellers' ads.txt authorization on any website. It is available as a Chrome add-on and is completely free to use.

With Adstxter, you can easily detect missing sellers in ads.txt files with just one click. Simply enter the sellers you want to test in the input field of the Adstxter window, and the tool will run a test on the currently open site to see if those sellers are present.

One of the key features of Adstxter is that it saves the entered sellers across browser sessions until they are replaced or removed. This allows you to easily keep track of your sellers and their authorization status.

When the Adstxter window is closed, the tool remains inactive and does not use any system resources. This ensures that it has minimal impact on your system's performance and does not intrude into your browsing experience.

Adstxter follows the IAB Tech Lab's ads.txt specification for the implementation of testing. However, please note that checking ads.txt files on subdomains is currently not supported.