libmime
Encode and decode quoted printable and base64 strings
libqp
Encode and decode quoted-printable strings according to rfc2045
quoted-printable
A robust & character encoding–agnostic JavaScript implementation of the `Quoted-Printable` content transfer encoding as defined by RFC 2045.
lettercoder
Quoted-printable (RFC 2045) and mime word (RFC 2047) decoding