Currently, release versions of PuTTY tools only run on full Win32 systems and Unix. ‘Win32’ includes Windows 95, 98, and ME, and it includes Windows NT, 2000, XP, and Vista.
In the development code, partial ports to the Mac OSes exist (see question A.3.6).
Currently PuTTY does not run on Windows CE (see question A.3.4), and it does not quite run on the Win32s environment under Windows 3.1 (see question A.3.5).
We do not have release-quality ports for any other systems at the present time. If anyone told you we had an EPOC port, or an iPaq port, or any other port of PuTTY, they were mistaken. We don't.
There are some third-party ports to various platforms, mentioned on the Links page of our website.