Local Port Checker
A browser-side self-check: which of the common ports on your own machine are reachable right now?
| Port | Service | State | Time |
|---|---|---|---|
| Results appear after scanning. | |||
Honest limits: browsers cannot open raw sockets — this checks 127.0.0.1 only, reports "reachable" instead of "open", and cannot identify services. For remote hosts use a real scanner.
Privacy: probes go straight from your browser to 127.0.0.1 — nothing is uploaded or stored.
How to use
- Press Scan — the tool probes about 20 common ports on 127.0.0.1 from your browser.
- Read the table: reachable (something is listening), closed, or inconclusive timeout.
- Remember the limits: localhost only, no banners or versions, nothing uploaded.
Frequently asked questions
Why can this tool only scan localhost?
Browsers do not expose raw TCP sockets, so a web page cannot connect to arbitrary hosts and read banners. What it can do is attempt connections to your own machine (127.0.0.1) and observe whether they succeed — enough to tell which of your local dev servers are running, and nothing more.
How does it detect a port from a web page?
It issues fetch requests with CORS-disabled mode to http://127.0.0.1:PORT. A response — even an opaque one — means a TCP connection was established, i.e. something is listening. An immediate rejection means nothing answered. Timeouts are reported honestly as inconclusive.
What does "open" really mean in the results?
"Reachable" would be more precise: the browser established a connection, so a service is listening. It cannot tell you what software is running or its version — that requires reading data, which browsers do not allow.
Can this tool scan other machines on my network?
No — and that is by design of the browser sandbox, not a missing feature. Point it at other hosts from a terminal (nmap or similar), not a web page.
Is anything about my machine uploaded?
No. The probes go directly from your browser to 127.0.0.1 and nowhere else; results are shown locally and never sent or stored.