SEO4Ajax Companion is a free Chrome extension that allows users to test the implementation of the Google Ajax Scheme directly in their browser. As an add-on in the Browsers category, this tool is designed to help developers ensure their websites are properly implementing the Google Ajax Scheme specification.

To use the extension, simply open the URL of any website that implements the Google Ajax Scheme specification. The extension will then check if the website is respecting the specification and append the query parameter "_escaped_fragment_=" to the URL if it is. This allows users to preview exactly what compliant bots see, as the extension disables JavaScript.

One of the key features of SEO4Ajax Companion is its ability to provide a visual indication of whether the snapshot of the page has been properly served. The color of the extension icon turns green to signify that the page snapshot has been served correctly.