TcpCatcher is a TCP and HTTP/HTTPS (1.0 and 1.1) proxy monitor server software. It will outstandingly help you debug any client-server software by displaying tcp packets. Since TcpCatcher is not a sniffer but an actual proxy server it will allow you to modify packets on the fly manually or programmatically.
As an educational tool, TcpCatcher will help understanding any tcp based protocol. Fully multi-threaded and 100% java based, it is portable, fast and reliable and it has many useful extra features like sorting, filtering, built-in search engine, dec/hex packet editor to help you analyze captured traffic.
TcpCatcher can be run as well as a desktop software as a background process launched from the command line or from its api.

Requirements:
* java

The license of this software is Freeware, you can free download and free use this protocol analyzer software.