Quoted-Printable Encoder

Quoted-Printable encoder and decoder

Quoted-Printable is the MIME content-transfer encoding defined in RFC 2045 §6.7. It is designed for content that is mostly readable ASCII with the occasional 8-bit character — accented names, currency symbols, em dashes — that must survive transport over older 7-bit email systems. This tool converts text both ways: pick Encode to turn plain text into Quoted-Printable, or Decode to read a Quoted-Printable email body back into normal text. It is handy for debugging raw email source, MIME parts, and Content-Transfer-Encoding: quoted-printable payloads.

How it works

On encode, the text is converted to UTF-8 bytes and each byte is examined. Printable ASCII (codes 33–126), spaces and tabs pass through unchanged. The = sign itself is always escaped to =3D so it is never ambiguous. Every other byte — control characters and any 8-bit byte from non-ASCII characters — becomes an = followed by its two-digit uppercase hex value, such as =C3. A newline becomes a hard CRLF line break, and to respect the format’s 76-character limit the encoder inserts a soft break (= then CRLF) before a line would grow too long.

On decode, soft breaks (= immediately before a line break) are removed, then each =XX sequence is read as a hex byte. The collected bytes are decoded back as UTF-8. An = not followed by two valid hex digits is rejected as invalid.

Example

Encoding the text Café — résumé costs €5. produces:

Caf=C3=A9 =E2=80=94 r=C3=A9sum=C3=A9 costs =E2=82=AC5.

Here é (UTF-8 C3 A9) became =C3=A9, the em dash — became =E2=80=94, and the euro sign € became =E2=82=AC. Plain letters and the trailing 5. are left untouched.

All encoding and decoding runs in your browser; your text never leaves your device.