I'm always hearing about FoundationDB but not much about who uses it. I know Deno and obviously Apple is using it. Who else? I'd love to hear some stories about it.
My company (Matterport, YC Winter '12) uses it to store metadata about 3d models. I really don't have that much to say about it because it's not my primary area of focus, and besides that, has been extremely reliable and hands-off, administration-wise. I particularly love that you can change redundancy modes on the fly, for example those listed here[1], and FDB will automatically re-arrange data to your liking, all without downtime. It handles offline/missing or replacing nodes quite well, and I credit my coworker's great efforts to make it work on top of Kubernetes for making our lives so much easier.
At s2.dev (a serverless datastore for real-time streaming data), we started with DynamoDB for our metadata store, but our access patterns kept running into per-partition throughput limits. We switched to FoundationDB, and it’s been great so far.
There might be a good reason for the lack of stories. FoundationDB runs critical infrastructure I work on, but I never actually have to think about it.
I've never spent less time thinking about a data store that I use daily.