A few things I haven't seen in the comments which I'm really happy with are:
- Vikunja
- Scrutiny
- Kimai
Other things which were mentioned already:
- Searx-ng
- Gitea
- Paperless-ngx
- Calibre-web
- Matrix (synapse)
- Nextcloud
- Jellyfin
- Uptime Kuma
- Mealie
- FreshRSS
- Vaultwarden
- Photoprism
All running in docker containers behind a caddy proxy.
If you're looking for just filesharing capabilities, OwnCloud might be a good alternative. It's recently been rewritten in Go and its supposedly quite fast. I must say that I haven't used it myself.
Another alternative could be Nextcloud, but that comes with a whole suite of other software such as calendar, contacts, ...
I've also heard some good things about seafile, but never used it myself either.