Wow, this looks great. Self-hostable but with an easy to use public instance, no app and a decent UI.

A few things I would really like to see added seem to already be in discussion, such as an "add to homescreen" option (https://github.com/xMartin/grouptabs/issues/146, https://github.com/xMartin/grouptabs/pull/143) and a delete option (https://github.com/xMartin/grouptabs/issues/152).

I look forward to playing with!