Google (not saying it's a good search engine, but people use it) puts putty.org at the top of search results.
The results shows as:
Download PuTTY - a free SSH and telnet client for Windows.
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...
The results shows as: