⌘ K
mime · 7-bit safe · soft line wrap · live

Encode and decode Quoted-Printable

MIME Quoted-Printable encoding for email bodies and headers. Keeps ASCII readable while escaping high-bit bytes as =XX. Honours the 76-character soft wrap. All processing runs locally.

Quoted-Printable Converter
Input
33 B
1 lines
Output
106 B
2 lines
Status
ready
live
Ratio
3.21×
out/in
input · text
output · quoted-printable
Caf=C3=83=C2=A9 r=C3=83=C2=A9sum=C3=83=C2=A9 =C3=A2=E2=82=AC=E2=80=9D na=C3=
=83=C2=AFve fa=C3=83=C2=A7ade
Quick Start

How to convert Quoted-Printable

Bytes 33–126 (except =) pass through. Tabs and spaces stay readable. Everything else becomes =XX. Lines longer than 75 chars get a soft = wrap.

  1. 01

    Pick direction

    Encode for outgoing email bodies; decode for raw inbound payloads.

    Bytes flow through TextEncoder/TextDecoder for predictable UTF-8 semantics — emoji, surrogate pairs, and combining marks all encode losslessly.

    modeUTF-8TextEncoderlosslesslive
    mode · raw bytesencode · UTF-8
    text → =XX
    loaded · UTF-8MIME · ready
  2. 02

    Paste content

    UTF-8 input — accents, em-dashes, anything above 7-bit ASCII.

    Hash and signature operations call crypto.subtle from the Web Crypto API, so output matches OpenSSL / Node bit-for-bit.

    inputWeb Cryptosubtledeterministiclive
    input · optionsCafé · live
    Café résumé
    options applied · livelive
  3. 03

    Live encode

    High bytes become =XX, lines wrap at 76 chars.

    Options re-run instantly through useEffect + useMemo — switching URL-safe mode or padding doesn’t re-encode from scratch.

    livememoisedoptionsinstantreactive
    out · encodedqp · ready
    Caf=C3=A9 r=C3=A9sum=C3=A9
    encoded · livelossless
  4. 04

    Copy or download

    One click to clipboard. Download as .txt.

    Copy uses the Async Clipboard API; downloads ship via Blob with the appropriate MIME (text/plain, image/png, …) so external tools recognise them.

    exportclipboardblobMIME-correctclient-side
    ok · copiedready · done
    Copied
    shipped · ready to shipsuccess
Pro tips

Encoding without surprises

Always UTF-8 first

Use TextEncoder / TextDecoder for bytes ↔ string conversion. btoa alone breaks on non-ASCII.

URL-safe vs standard Base64

Standard uses +, /, =; URL-safe swaps to -, _, no padding. Don’t mix them.

Hashes aren’t passwords

SHA-256 is fast; that’s good for fingerprints, bad for passwords. Use bcrypt / argon2 for credentials.

Watch padding rules

Some decoders are strict about = padding, others auto-pad. If round-trips fail at exactly 1 or 2 bytes, check padding.

Use Web Crypto for keys

Generate cryptographic keys via crypto.subtle, never Math.random. The latter is predictable.

JWT decode ≠ verify

Decoding a JWT just splits and base64-decodes. Verification needs the issuer’s public key / shared secret.

Related toolsBase64 EncoderBase64 DecoderHTML EncoderURL EncoderUnicode ConverterText to Hex
Use Cases

When to use Quoted-Printable

Email, MIME headers, archival formats.

Email bodies

RFC 2045 Content-Transfer-Encoding for text/plain. Output round-trips losslessly with the matching decoder — both run client-side, so end-to-end testing happens in a single tab. Encoding flows through TextEncoder for predictable UTF-8 semantics.

RFC-compliant

MIME headers

Encoded-word format =?utf-8?Q?…?= uses QP internally. Web Crypto's subtle.digest produces output that matches OpenSSL, GPG, and Node's crypto module byte-for-byte. That makes the result trustworthy as a content fingerprint, ETag, or integrity check.

OpenSSL-matched

Mailing list archives

Raw .mbox files often contain QP-encoded text. Pairs cleanly with HMAC, JWT, and signed-URL workflows where bit-level correctness matters. The browser's crypto stack is FIPS 140-validated in Chrome and Firefox, so it's production-grade.

lossless

SMTP debugging

Read raw 7-bit-safe payloads from telnet sessions. Output uses canonical RFC 4648 / 7515 alphabets so curl, openssl, and any standards-compliant decoder accept it as input. URL-safe variants drop padding for tokens that travel in query strings.

byte-identical

Legacy systems

Older gateways prefer QP over Base64 for text. Heavy hashing runs through useMemo so large inputs don't block typing. PBKDF2, bcrypt, and Argon2 expose configurable cost factors — tune for your threat model, not the default.

spec-grade

i18n testing

Confirm accents round-trip through 7-bit transports. Same input plus same options always yields identical bytes. That's the foundation for content-addressed storage (IPFS, Git, S3 ETags) and means the output is safe to commit to fixtures.

i18n
FAQ

Frequently asked questions

QP keeps ASCII readable. For mostly-ASCII content (English with the occasional accent), QP is more compact and inspection-friendly than Base64.
An = followed by a newline. Receivers strip it; senders insert it to keep lines under 76 characters as RFC 2045 requires.
Encoding takes UTF-8 in. Decoding produces UTF-8 out. The QP layer transports bytes — UTF-8 is just the most common byte stream to wrap.
Header encoding (encoded-words) has stricter rules — for example space → _ — handled by a separate spec. This tool implements body encoding.
No. Encoding and decoding run locally in your browser.
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