We actually use HNSWLIB by NMSLIB on the backend. NMSLIB is solving the approximate nearest neighbor problem, not the storage problem. It’s not a database, it’s an index. We handle everything needed to turn their index into a full fledged database with a data science workflow around it (versioning, monitoring, etc.)

That's great. I've been very impressed by the performance of nmslib in my scenarios. I'll definitely check out eh - thanks for sharing!