- KeyDB (https://keydb.dev)
- Pelican Cache (https://www.pelikan.io/)
- Tendis (https://github.com/Tencent/Tendis)
- SSDB (https://github.com/ideawu/ssdb)
- Dynomite (https://github.com/Netflix/dynomite/)
- Dragonfly (https://github.com/dragonflydb/dragonfly)
- Skytable (https://github.com/skytable/skytable)
- Tidis (https://github.com/yongman/tidis)
- Anna (https://github.com/hydro-project/anna)
- Skyhook (https://github.com/aerospike/skyhook)
And some which are kinda dead but still interesting -- redis is the kind of workload that does actually become feature complete so these are still usable in my mind though maybe not first choice:
- ledisdb (https://github.com/ledisdb/ledisdb)
- Codis (https://github.com/CodisLabs/codis)
- xcodis (https://github.com/ledisdb/xcodis)
I'm planning on doing a comparison with these at some point, because they're fascinating (all these projects go off in subtly different directions, I'll spare you the details), but here's a recent comparison someone else did:
https://news.ycombinator.com/item?id=31796311
Basically, redis compatibility is like step 1 for any KVS that wants to seem at least a little usable/real-world-focused so you get so many cool entrants.
I don't really personally keep up with redis for the stream use-case -- it's a great use for redis but that doesn't really make/break for me usually.