Developer Tools
Look Up a Port Number
Port Number Lookup for quick browser-based work with focused input and copy-ready output.
| Port | Common service |
|---|---|
| 443 | HTTPS |
To find open ports for a host, use a network scanner such as nmap from a machine where you have permission to scan.
Direct Answer
Use the Port Number Lookup when you see a port number in a URL, log file, firewall rule, or error message and need to know what service it's typically associated with.
The Three Port Ranges
Port numbers run from 0 to 65535 and are divided into three ranges managed by IANA, each with a different purpose and level of official assignment.
- Well-known ports (0-1023) are reserved for standard, widely used services like HTTP, HTTPS, and SSH.
- Registered ports (1024-49151) can be requested and registered with IANA by software vendors for specific applications.
- Dynamic or ephemeral ports (49152-65535) are assigned temporarily by the operating system for outgoing client connections.
- A single service's official port assignment is just a convention; nothing prevents running it on a different port unless a client hardcodes the default.
Ports You'll Run Into Constantly
A handful of port numbers cover most of the services developers deal with day to day, and recognizing them on sight saves a lookup most of the time.
- 80 and 443 for HTTP and HTTPS web traffic.
- 22 for SSH, 21 for FTP, and 25/587 for SMTP mail submission.
- 3306 for MySQL, 5432 for PostgreSQL, 6379 for Redis, and 27017 for MongoDB.
How to Use Port Number Lookup
- Open the tool on this page.
- Enter or paste your input in the field provided.
- Review the result shown on the page, then copy or download it.
Reference
| Feature | Details |
|---|---|
| Purpose | Complete the utility task shown on this page. |
| Input | The value or content requested by the tool. |
| Result | The generated or processed output shown on the page. |
| Best for | Quick browser-based utility work. |
| Category | Developer Tools |
| Works on | Desktop, tablet, and mobile browsers |
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Frequently Asked Questions
What port does HTTP use? What about HTTPS?
HTTP uses port 80 by default, and HTTPS uses port 443. Both are well-known ports, which is why browsers connect to them automatically without the URL needing to specify a port number.
What is port 22 used for?
Port 22 is the well-known port for SSH (Secure Shell), used for encrypted remote login and command execution on servers. It's also commonly used as the underlying transport for SFTP and Git-over-SSH connections.
What's the difference between well-known, registered, and ephemeral ports?
Well-known ports (0-1023) are reserved for standard services and typically require elevated privileges to bind on Unix-like systems. Registered ports (1024-49151) can be reserved by vendors for specific applications through IANA. Ephemeral ports (49152-65535) are assigned temporarily by the OS for the client side of outgoing connections and are reused once the connection closes.
Why do I see a random high port number in my browser's network tab?
That's the ephemeral source port your operating system assigned to the outgoing connection, not the destination port. The server is still being reached on its normal port, like 443 for HTTPS; the random high number just identifies your side of that specific connection.
What does 'port already in use' mean?
It means another process on the same machine is already bound to that port and listening on it, so a new process can't bind to the exact same port and address combination. Stopping the other process, or configuring the new one to use a different port, resolves it.
Can two applications use the same port number at the same time?
Not for the same protocol, IP address, and port combination simultaneously as a listener; only one process can bind and listen on a given port at a time on a given interface. However, TCP and UDP maintain separate port spaces, so one application can use TCP port 5000 while another uses UDP port 5000 without conflict.
What ports do common databases use by default?
MySQL defaults to port 3306, PostgreSQL to 5432, Redis to 6379, and MongoDB to 27017. These are all in the registered range and can be changed in configuration, but most tools and drivers assume the default unless told otherwise.
Why would a firewall block a specific port?
Firewalls commonly block ports to reduce the attack surface, since an open port that's listening for connections is a potential entry point. A blocked port can prevent a legitimate service from being reached even though the service itself is running correctly, which is a common cause of connection timeouts that aren't actually application bugs.