UTM Parameter Testing is a free Chrome extension developed by Darren Smith. This extension allows users to quickly add UTM parameters to the end of their current URL. With just one click, users can add UTM Content, UTM Source, UTM Term, and UTM Medium to the URL of the current tab. This is particularly useful for testing if URL parameters are properly populating in forms.

The latest version, 1.5, introduces a new feature where the extension's button will remove any existing query string present in the URL. This ensures that users can easily replace or update the existing UTM parameters without any interference.

UTM Parameter Testing is a valuable tool for marketers, web developers, or anyone who needs to test and track the performance of their URLs. With its simple and intuitive interface, adding UTM parameters to URLs has never been easier.