Since Firefox 57 I've switched over from Chrome. This extension initially did not log correctly even though the notes here said it added support for Firefox 57. However, I recently received an update to my rescuetime OSX app and now everything works perfectly as expected. Thanks rescuetime. This is now a 5 star extension.

Best way to keep track of what you actually get up to on the internet all dang day - warning: may be eye opening.

Using the latest 57.0b9 on both standard and developer editions of Firefox for Mac, after installing the RescueTime add-on I can link it to my account just fine, and if I click on the icon in the toolbar the summary does correctly identify which site I'm on.

*But* it never logs any time on these sites. If I visit a site I've not seen in Chrome that day it always reports it as being my first visit. If I visit a site I've seen in Chrome it reports the previous total time spent there but never increments.

Good overall addon, and now works with Firefox 57+