Online Port Scanner
Scan any host for open TCP ports directly from the browser, no install required. Check a default list of common service ports or specify your own comma-separated list. Each result shows open or closed status with connection latency, useful for verifying firewall rules, checking if a service is actually listening, or auditing your own infrastructure.
Live checking is discontinued
ProxyChecker.dev no longer runs proxy checks, the API, MCP tools or paid plans. Nothing on this site tests a proxy anymore. The guides below still explain how proxy testing works and what to look for.
Need working proxies? These are the two providers we tested with:
Frequently asked questions
Is it legal to port scan a website?
Scanning your own infrastructure is always fine. Scanning systems you don't own or manage without permission can violate terms of service or, depending on jurisdiction, computer access laws. Only scan hosts you're authorized to test.
Why is a port showing closed when I know a service is running?
A firewall may be blocking the port from this scanner's network location, the service may only bind to localhost instead of all interfaces, or a security group/ACL may allow your IP but not this checker's IP.
What ports should I check by default?
Common defaults include 21 (FTP), 22 (SSH), 25 (SMTP), 80/443 (HTTP/HTTPS), 3306 (MySQL), 5432 (Postgres), and 6379 (Redis). You can override this with any custom comma-separated port list.
Does an open port mean the service is vulnerable?
Not by itself. An open port just means something is listening. Whether it's exploitable depends on the service, its version, and its configuration, an open port is a starting point for further investigation, not a vulnerability finding on its own.