Port Listener v2.00 - TCP Port Monitoring Tool
Listen on TCP ports, view live connections, and test HTTP reachability from one lightweight utility
A Network Debugging Tool That Works for You
Need to verify that a port is open and reachable on your Windows machine? Whether you are troubleshooting a firewall rule, confirming that a service is listening, or testing connectivity between applications, Port Listener gives you instant, real-time feedback without complex configuration or heavyweight network analyzers.
Originally developed to test error conditions in our own software, Port Listener has grown into a fully featured TCP port monitoring utility trusted by developers, system administrators, and security professionals. Version 2.00 is a complete rewrite from the ground up -- now with live TCP/IP connection monitoring, built-in HTTP response handling, system tray support, and timestamped logging.
Simply specify a port, click Start Listening, and watch connections arrive in real time. Port Listener automatically detects whether incoming traffic is an HTTP request and responds with valid HTML, or sends a plain-text welcome message for raw TCP connections. Run multiple instances simultaneously to monitor several ports at once -- each one runs independently.
Who Is This For?
Key Features
Fully Portable -- Zero Installation
How to Get Started
Command Line Options
Pass a port number on the command line to auto-start listening and minimize to the system tray:
listener.exe [port number]
Sample Responses
HTTP Request -- When Port Listener detects an HTTP request, it responds with a valid HTML page:
HTTP/1.1 200 OK
Content-Type: text/html; charset=UTF-8
<html>
<head><title>Port Listener v2.00</title></head>
<body>
<h2>Port Listener is working!</h2>
</body>
</html>
Raw TCP (Telnet) -- Plain text response for non-HTTP connections:
Welcome to the Port Listener Server on port [portnumber]
Port Listener v2.00 - Windows Support
Win 11
Win 10
Win 8
Win 7
Server 2022
Server 2019
Server 2012
Server 2011
Server 2008 R2
Screenshots
Main Interface
The main screen lets you specify a TCP port to listen on. Click Start Listening to begin monitoring incoming connections.
HTTP and TCP Responses
Port Listener detects HTTP requests and responds with a valid HTML page, confirming that your port is reachable from any browser.
Telnet and raw TCP connections receive a plain-text welcome message confirming connectivity on the specified port.
Using Postman to make an HTTP request -- Port Listener detects the request type and responds with the appropriate HTML.
A PowerShell script creates a TCP connection to Port Listener, which receives the message and sends back a plain-text response.
System Tray and Notifications
When you first minimize Port Listener, a balloon hint explains how to interact with the app from the Windows taskbar.
Hover over the system tray icon to see the current listening status and port number.
Right-click the tray icon for quick access to restore, stop listening, or exit the application.
Tips and Troubleshooting
If the port you selected is already in use by another application, Port Listener will display an error message so you can choose a different port.
Always allow both public and private network access when Windows Firewall prompts you, otherwise Port Listener cannot receive connections.
Walkthrough
A complete walkthrough: listening on port 8080, opening Firefox to localhost:8080, and seeing the HTTP response and raw headers in Port Listener.
Version History
Complete rewrite of the software from the ground up.
This version only supports Windows 7, 8, 10, 11 and Windows Server 2008, 2011, 2012, 2019, 2022 and newer.
Removed UDP support (did not work on newer Windows versions).
Added detection of HTTP requests with valid HTML response.
Raw TCP sockets now send a welcome message when a client connects.
Added option to include timestamps in the log.
Added option to clear the log each time listening starts.
Added Windows System Tray support.
Command-line port number now auto-minimizes and starts listening.
Corrected min and max port numbers for new Windows restrictions.
Added a command-line option to pass in the port number.
Added a connection type of TCP or UDP.
Defaulted to TCP.
Minor spelling corrections.
Added Port Data View to see incoming data on the port.
Increased ports to 999999.
Enhanced error handling for exceptions.
Corrected issues with the tray icon restore state.
Initial version.
Download Port Listener
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Learn MoreSupport Port Listener Development
Port Listener is completely free. If this tool has saved you time or simplified your network troubleshooting, consider making a donation to help fund continued development and new features.
Support and Information
Find answers to common questions about Port Listener.
View FAQFound a bug or have a question? We are here to help.
Contact UsTo uninstall, simply delete the program folder. No registry entries or system files are left behind.
Download the latest version and extract over your existing folder, or to a new location. Settings are preserved.