PuTTY is a free implementation of SSH and Telnet for Windows and Unix platforms, along with an xterm terminal emulator.
Modemu2k is a fork of modemu, originally developed by Toru Egashira. Modemu2k adds telnet capability to a comm program. It can redirect telnet I/O to a pty so that a comm program can handle the pty as a tty with a real modem, and allows you to use a comm program's scripting and file transfer features over telnet.
TinTin++, aka tt++, is a free Mud Client for Android, Windows, Linux, and Mac OS X that runs in console mode. Its main assets are a easy to learn and use scripting language featuring just-in-time compilation, full telnet support, automapping, perl-compatible regular expressions, a split screen interface to separate mud output from client input, and keyboard macros that work on all systems. TinTin++ runs on Windows using the Cygwin Linux environment, and on Android using the Termux Linux envi
A telnetd server with a IPv6 support, chroot support, allow/deny via user, IP and MAC address, and which has it's own native authentication so that telnet accounts cannot be used to log into the main system.
ExtraPuTTY is a fork of Putty 0.63 for Windows. It adds a Win32 API, command shortcuts, uses config files instead of the registry, automatic reconnection, and supports FTP, TFTP, X/Y/Zmodem besides SSH and Telnet. It also provides Lua 5.2 scripting for session handling and management, and is directory relocatable for portable installations.