Open Port Checker: Test HTTP, HTTPS, and WebSocket Ports
Open Port Checker is a best-effort browser port probe. Enter a host and port, and it uses browser fetch with no-cors and WebSocket to look for HTTP(S) or WebSocket-speaking services. Browsers cannot open raw TCP sockets and block restricted ports such as SSH and SMTP, so a result cannot prove a port is open or closed. Use the included nc and nmap command suggestions for definitive checks.
Open Port Checker is a best-effort browser port probe for checking whether a host and port appear to offer an HTTP(S) or WebSocket-speaking service. It provides a quick way for developers and DevOps engineers to investigate a connection, but it cannot definitively determine whether a port is open or closed.
To check a target, enter its host and port. The tool uses browser fetch with no-cors and WebSocket to attempt detection. Browsers cannot open raw TCP sockets, and they block restricted ports such as SSH and SMTP. As a result, browser-based probing has important limits: a missing response does not establish that a port is closed. Open Port Checker includes nc and nmap command suggestions for definitive results.
A browser probe and a command-line port check are not interchangeable. The browser methods can look for HTTP(S) or WebSocket-speaking services, while browsers cannot make the raw TCP connections needed for a definitive port check. Use the browser tool for a quick initial signal, then turn to nc or nmap when you need a conclusive result.
The tool runs in your browser, but checking a target requires network access: the host and port you enter are sent to that host as part of the connection attempt. My-DevTools stores nothing. Open Port Checker does not work offline because it must reach the target. It can help developers and DevOps engineers investigate service endpoints while keeping the limits of browser-based checks clear.
Step 1: Enter the host and port you want to check. The tool needs these details to attempt a connection to the target.
Step 2: Run the check in your browser. Open Port Checker uses fetch with no-cors and WebSocket to look for HTTP(S) or WebSocket-speaking services.
Step 3: Review the result as a best-effort signal, not a definitive statement that the port is open or closed. Browser restrictions can affect what the probe can detect.
Step 4: For a definitive check, use the suggested nc or nmap commands. These command-line tools can perform checks that a browser-based probe cannot.
Use case: Use Open Port Checker as an initial check when assessing whether a host and port meet a connectivity requirement. Treat the browser result as a signal, then confirm with nc or nmap.
Use case: Check a service endpoint before sharing it with a reviewer or user, so you can spot a possible connection issue early. A negative browser result does not prove that the port is closed.
Use case: Give a port-status assessment with the right context instead of treating a browser result as a definitive verdict. Follow up with nc or nmap when you need confirmation.
Use case: Check whether a host appears to offer an HTTP(S) service from your browser. The probe is useful for an initial check, but it cannot test raw TCP connectivity.
Use case: Make an initial check for a WebSocket-speaking service on a host and port. If you need a definitive result, use one of the suggested command-line checks.