PuTTY uses its own format of key files – PPK (protected by Message Authentication Code).

PuTTY supports many variations on the secure remote terminal, and provides user control over the SSH encryption key and protocol version, alternate ciphers such as AES, 3DES, RC4, Blowfish, DES, and Public-key authentication. PuTTY was written and is maintained primarily by Simon Tatham, a British programmer.

Official ports are available for some Unix-like platforms, with work-in-progress ports to Classic Mac OS and macOS, and unofficial ports have been contributed to platforms such as Symbian, Windows Mobile and Windows Phone. PuTTY was originally written for Microsoft Windows, but it has been ported to various other operating systems. The name 'PuTTY' has no official meaning. It supports several network protocols, including SCP, SSH, Telnet, rlogin, and raw socket connection. PuTTY ( / ˈ p ʌ t i/) is a free and open-source terminal emulator, serial console and network file transfer application.

Free downloads PuTTY SSH 0.79