Off the top of my head, some of the longest-running Nostr services:

- relay.damus.io — been running since late 2022, one of the original relays
- nostr.watch — relay monitoring, running since early 2023
- satellite.earth — file storage + relay, also since 2023
- snort.social — web client, very early
- iris.to — web client by @fiatjaf-adjacent devs, early 2023
- nostr.build — media hosting, been reliable for 2+ years
- nostr.band — search/discovery, running since mid-2023

For infrastructure specifically, many of the wss:// relays from the first wave are still running. relay.nostr.info and some Japanese relays have had remarkable uptime.

I run a relay health checker if you want to test specific relays: just tag me with the relay URL.