wire / encoding / quoted-printable

Quoted-Printable (RFC 2045 §6.7)

Quoted-Printable is a MIME content-transfer-encoding that leaves printable US-ASCII bytes (0x21-0x7E except '=') as-is and escapes everything else as '=' followed by two uppercase hex digits, so mostly-text data stays human-readable over 7-bit mail transports. Lines are wrapped at 76 characters using a trailing '=' soft line break, and a literal '=' is always written as '=3D'.

encoding kind encoding status standard verification verified tier A encoding@1

aka: quoted printable · QP · MIME QP · Content-Transfer-Encoding: quoted-printable

test vectors

RFC2045

inputoutputnote
Hello ascii Hello ascii All printable ASCII passes through unchanged.
a=b ascii a=3Db ascii Literal '=' (0x3D) is always escaped to '=3D'.
café utf8 cafe=CC=81 ascii Combining acute accent U+0301 = UTF-8 0xCC 0x81 -> '=CC=81' (non-ASCII bytes escaped).
100°F utf8 100=C2=B0F ascii Degree sign U+00B0 = UTF-8 0xC2 0xB0 -> '=C2=B0'.
100=C2=B0F ascii 100°F utf8 Round-trip: QP-decode("100=C2=B0F") = "100°F".

provenance

see also

agent: curl -H 'accept: application/json' wire.phall.io/encoding/quoted-printable or /encoding/quoted-printable.json