Port 3000: Dev servers / Grafana
Port 3000 is a common default for web development servers and self-hosted apps like Grafana.
What runs on port 3000
Ruby on Rails, many Node.js frameworks and React tooling default to 3000 for development servers. Grafana dashboards and Gitea use it by default, and AdGuard Home runs its first-time setup wizard on 3000.
On a home network
Home servers and Raspberry Pis running Grafana, Gitea or AdGuard Home listen on 3000, as do developers' laptops while a project is running.
If port 3000 is reachable from the internet
A development server exposed to the internet can leak source code, debug information or unfinished features. Self-hosted apps like Grafana are fine behind a login when kept up to date, but default admin passwords and old versions are common. Expose these through a VPN or a reverse proxy with authentication, not a raw port forward.
How to check whether it is open on your network
Check the app's own login settings and your router's forwarding list for 3000. RECON's Port Scan will show which device on your LAN serves it.
To find out whether port 3000 is open on something in your home, and whether the internet can reach it, the app scans your Wi-Fi from your phone and checks your public address from the outside. It says what it checked and what it could not. Get RECON for iPhone — one-time purchase, no account, nothing leaves the device.