putty.exe from Putty-CAC, an improved version of Putty-SC adds PKCS#11 support to putty, which the upstream version does not have. It works flawlessly with OpenSC PKCS#11 module. A fork of Putty, named KiTTY also exists.
Using the pageant.exe from Putty-CAC allows to use WinSCP with smart cards as well.
See [[OpenSSH-and-smart-cards-PKCS#11]] for more information.
[[PuTTYcard|PuTTYcard]] is another, independent implementation to add smart card support to putty.
Read more about it [[here|PuTTYcard]].