I have a specific requirement for zap.store that no relay provides out of the box, custom indexing multiple fields for NIP-50 full-text search (and rejecting certain event kinds).
I thought of customizing the fiatjaf golang relay framework but didn't want to learn new tooling just for this.
nostr:npub1gzuushllat7pet0ccv9yuhygvc8ldeyhrgxuwg744dn5khnpk3gs3ea5ds pointed me at Bun.sh which is a powerful JS toolkit with built-in websockets and sqlite, and I basically got a relay implemented in under a day... very cool.
This will eventually index all software releases on zap.store, and I'm thinking of making this same server implement nostr:npub1ye5ptcxfyyxl5vjvdjar2ua3f0hynkjzpx552mu5snj3qmx5pzjscpknpr-Blossom, keeping copies of all the indexed artifacts.
#zapstore
Oh yes, bun.sh! It crossed by multiple times now and I've wrote down a todo to research this tool further.. Thx for the reminder, because https://bun.sh/docs/api/websockets#connect-to-a-websocket-server is really looking interesting to build a proof-of-concept Nostr client with it. My choice would be to include it in a Vue project as I'm familar with that framework.
And yes as you're saying, basicly you can also build a relay implementation with it...how cool!
not sure it's meant to be used in the browser but for servers it's damn good!
For sure it's also meant for clients! 😉
Look at this list: 
#e97600aab8d8d5c3d290f881b39f7366631d159c0cdf20eb07cf2e154a25570c which could find at the bottom of https://bun.sh
