ServTerm

ServTerm is a winsock tool which can assist you in debugging client/server communications. You can make it act as a server (eg, a web server or mail server) to examine the data that clients transmit.

ServTerm itself transmits data line-by-line to mimic server behaviour. You can also use ServTerm in client mode, in which case it acts like a telnet program except that you can scroll back to see previous output and transmit data line-by-line.