Finally, something that allows you to comfortably work with Firefox after 57.
A very nice combination of contexts with grouping cards. Still far from the functionality of Tab Groups, but this is due to the limitations of the current api and not the extension itself. Conex, by the way, "squeezes" almost everything that is possible from the current api.
Most lacking feature is synchronization between devices (but again, this is probably a limitation of Firefox contexts, not the extension itself).