Five stars.

Bugs should be expected whilst this extension is explicitly experimental. Some of the technologies used, or to be used, by this extension are quite novel – or not yet provided by Mozilla … and so on.

Whilst it's not intended for use with anything less than Firefox 57.0a1, I do use Conex with 56.0.1 – and expect to continue with 56.x until the August 2018 release of Firefox 62.

https://wiki.mozilla.org/RapidRelease/Calendar#Future_branch_dates

Special attention to a preference that can be chosen when beginning to use Conex – "don't care about privacy" – I do care. Simply:

- in the Firefox profile where I allow carelessness with Conex, I will not use Firefox containers for anything privacy-related.

(There's just one container – used for testing the new front-end to addons.mozilla.org – entirely unrelated to privacy.)

Conex is, amongst other things, useful for switching tabs. I currently use it with more than one thousand tabs in seventy-something groups (the traditional Tab Groups extension) across fourteen windows. Hint:

- it's sometimes easier to switch tabs with Conex than with Mozilla's address bar.

Seeking grouped tabs in Firefox 56: with Tab Groups, with Mozilla's address bar, and with Conex – https://www.youtube.com/watch?v=fDbLhJJGRQU

Where Firefox 56.0.1 switch to tab fails, Conex 0.0.65 succeeds – https://www.youtube.com/watch?v=YccPINbCePg