localhost:8123: what runs on it and how to open it
Port 8123 is the web address of Home Assistant. How to open it and fix problems.
Open this address: http://localhost:8123This opens on your own computer. It only works if the program is running.
localhost:8123 is the web page of Home Assistant. On a separate device such as a Raspberry Pi, you open its address, for example homeassistant.local:8123, from another computer.
What runs on localhost:8123
- Home Assistant on a Raspberry Pi, a mini PC or in Docker
Commands to start and test port 8123
curl -I http://localhost:8123docker run -d --name homeassistant --network=host -v ./config:/config ghcr.io/home-assistant/home-assistant:stablecurl -I http://homeassistant.local:8123Find what is using port 8123
Run these in a terminal on your computer. Nothing is sent to this site.
If localhost:8123 will not open
- homeassistant.local does not work
- Name lookup depends on your network. Use the IP address of the device with :8123 instead.
- The page takes long to load on first start
- The first start can take several minutes while it sets itself up.
- Port 8123 is already in use
- Another program is on this port. Find it with the tool below and stop it, or start yours on another port.
- This site can’t be reached (ERR_CONNECTION_REFUSED)
- The program is not running. Start it and keep that terminal open. See the full checklist.
- Works on your computer, not on your phone
- Start the server on all network addresses and use your computer’s IP address. See how to open localhost from your phone.
Other ports like 8123
| Port | Usually used by |
|---|---|
| localhost:11434 | Ollama (AI models) |
| localhost:5601 | Kibana |
| localhost:11501 | Not a standard port: check what is using it |
| localhost:9200 | Elasticsearch |
| localhost:5672 | RabbitMQ |
| localhost:15672 | RabbitMQ admin page |
| localhost:9090 | Prometheus |
Questions about localhost:8123
- Why does localhost not work?
- If Home Assistant runs on another device, localhost is your own computer. Use that device’s name or IP address.
- Is localhost:8123 safe?
- Yes, as long as it stays on localhost. Only your own computer can reach it. It becomes reachable from other devices only if you start the program on 0.0.0.0 or your computer's IP address. Do not put development or admin tools on the public internet.
- Can I use a different port instead of 8123?
- Yes. Most programs let you choose the port with a setting or a command option. Pick a free port above 1024 and open that number instead.
- How do I check what is using port 8123?
- Use the port checker on this page. It shows the command for Windows, macOS and Linux and does not send anything to this site.
- Can I open localhost:8123 from my phone?
- Yes, if both are on the same Wi-Fi. Start the program so it listens on all addresses, then open your computer's IP address with the port on the phone. A firewall on the computer can still block it.
Free tools that help
- Common ports listSearch a list of common TCP and UDP port numbers: SSH 22, HTTP 80, HTTPS 443, MySQL 3306, PostgreSQL 5432 and more, with dev server ports.