List of the 'best of breed' libre technologies, especially for education and learner collaboration

The #FOSSDLE #Commons project exists, in part, to test libre technologies to aid digital learning, aka 'Open Educational Technology' or Open #EdTech. We're keen to make others aware of the array of technologies we've implemented, to provide others in education the ability to 'kick the tyres' and see if they might find them useful or compelling for their own educational technology use cases. We also want to find out what other open / libre technologies (i.e. non-proprietary) technologies people in the Fediverse have found essential! Here's our list.