Note that WWW::Mechanize::Firefox only works with versions of Firefox before version 54, as Mozilla removed the capability for the old extension mechanism back then. WWW::Mechanize::PhantomJs still works, but PhantomJs itself stopped development.

WWW::Mechanize::Chrome is currently the only module that uses a supported browser version. Microsoft Edge uses the same protocol for automating the browser, but has a much more limited API. In teh future, maybe we can drive more than one browser using the same wire protocol.

Hopefully, Mozilla will implement the Chrome Developer Tools protocol as well some day. Then, WWW::Mechanize::Firefox can be revived.

Disclaimer: I'm the author of both modules.