TeraTerm Project would have been developed terminal emulator "Tera Term" and SSH module "TTSSH". This software is open source software under BSD License. This is Tera Term Pro 2.3 succession version and is being officially recognized by the original author. Development is continuing in Project Page on OSDN. You can download Tera Term from https://ttssh2.osdn.jp/.
PuTTY is an SSH and telnet client, developed originally by Simon Tatham for the Windows platform. PuTTY is open source software that is available with source code and is developed and supported by a group of volunteers. You can download PuTTY from http://www.putty.org/.