Free developer tool
MIME encoded-word converter
Encode plain text into RFC 2047 encoded-words and decode =?UTF-8?B?…?= subjects back to readable text.
Converter result
Encoded subject and decoded text
Both conversions run locally in your browser.
=?UTF-8?B?UsOpaW5pdGlhbGlzYXRpb24gZGUgdm90cmUgbW90IGRlIHBhc3NlIOKAlCBU?= =?UTF-8?B?ZW1wTWFpbGl0bw==?=
Subject: Welcome to TempMailito Confirm your inbox
Encoded-words belong in headers, not bodies. Keep each token under the 75-character limit when you paste results into fixtures.
What are encoded-words?
Email headers can only carry 7-bit ASCII, so non-ASCII subjects travel as =?charset?encoding?text?= tokens defined by RFC 2047. B means base64; Q is a quoted-printable variant where spaces become underscores.
QA use cases
- Verify localized subjects survive your sending pipeline.
- Debug mojibake subjects like =?UTF-8?B?…?= in received messages.
- Assert expected encoded subject values in automated tests.
- Prepare sample subjects for internationalization test suites.
Check subjects in a real inbox
Encoding is only half the story. Send your encoded subject to a temporary inbox and confirm how Gmail, Outlook, and other clients decode and display it.
Email template testing guideRelated guides
FAQ
Encoded-word converter questions
What is an encoded-word in MIME?
An encoded-word is an RFC 2047 token like =?UTF-8?B?SGVsbG8=?= that carries non-ASCII text inside 7-bit email headers, most often in Subject lines and display names.
What is the difference between B and Q encoding?
B encodes the text as base64 and suits non-Latin scripts. Q uses quoted-printable rules with underscores for spaces, so mostly-ASCII text with a few accents stays readable.
Why did my subject split into multiple encoded-words?
A single encoded-word is limited to 75 characters, so longer text must be split into several tokens. The converter splits on UTF-8 character boundaries, just like compliant mail libraries.
Does the converter support charsets other than UTF-8?
Decoding uses the browser TextDecoder, so common charsets such as ISO-8859-1 work too. Unknown or broken tokens pass through unchanged.
Is my text sent anywhere?
No. Encoding and decoding happen entirely in your browser with no network calls.