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MIME Encoded-Word Decoder

Decode MIME and RFC 2047 encoded words in email subjects, sender names, and other headers. Read UTF-8 Base64 or Q encoded text locally.

Paste a subject line, From display name, folded header, or plain text you want to decode or encode as a MIME encoded word.

Paste raw encoded words like =?UTF-8?B?...?=, full email header lines, or plain text you want to encode.

Options

Use decode mode for copied email headers, encode mode for new non-ASCII subject lines or display names, and analyze mode when you only want to inspect the structure.

Output

MIME encoded-word output will appear here.

Decode MIME and RFC 2047 Email Headers

Email subjects, sender names, and other message headers may appear as encoded text when they contain emoji, accented letters, Hindi, Japanese, or other non-ASCII characters. RFC 2047 represents this text as MIME encoded words so it can travel safely through email systems.

This MIME decoder reads patterns such as =?UTF-8?B?...?= and =?UTF-8?Q?...?=. It converts them into readable text and shows the charset, encoding method, byte length, folding issues, and other useful details.

How to Decode a MIME Email Subject

  1. Paste an encoded subject, From name, folded raw header, or plain text string.
  2. Choose whether to decode, encode, analyze, or normalize the header.
  3. Keep unfolding enabled when you paste raw multiline headers from an email source.
  4. Review the detected charset, encoding method, decoded preview, and warnings.
  5. Copy plain text, encoded-word syntax, JSON, Markdown, CSV, or a review checklist.

Base64 B Encoding and Q Encoding

MIME encoded words normally use either B encoding or Q encoding. B encoding stores the header bytes as Base64. Q encoding is similar to quoted-printable and often keeps readable letters visible while escaping special bytes with equals signs.

For short text with many ASCII letters, Q encoding can be easier to inspect. For emoji, non-Latin scripts, or mixed international text, Base64 is often cleaner and shorter.

RFC 2047 Encoded-Word Format

An encoded word follows the structure =?charset?encoding?encoded-text?=. The charset identifies how the original text was stored, while the encoding value is normally B for Base64 or Q for Q encoding.

These encoded words are commonly found in Subject, From, To, Cc, and comment fields. They are intended for email headers, not for encoding an entire email body.

Example Encoded Header

Subject: =?UTF-8?B?WW9yeWFudHJhIOKcqCBFbWFpbCBIZWFkZXIgVGVzdA==?=
From: =?UTF-8?Q?Varoun_Sonawane?= <hello@yoryantra.com>

Why Email Headers Look Broken

Raw message views, logs, CRM exports, support ticket systems, SMTP traces, and webhook payloads can show the encoded header instead of the decoded value. That does not always mean the email is broken. It usually means you are seeing the transport-safe representation of the header.

Problems usually happen when the encoded-word is split incorrectly, uses the wrong charset, mixes spaces badly between adjacent encoded words, or is copied from a folded header without proper unfolding.

Frequently Asked Questions

What is a MIME encoded-word?

It is an email header format used to represent non-ASCII text inside fields such as Subject, From, To, Cc, and comments.

Can this decode email subject lines?

Yes. Paste the full Subject header or only the encoded-word value, then run the decoder to get readable text.

Can it decode sender names in a From header?

Yes. You can paste a full From header containing an encoded display name and keep the email address visible in the decoded result.

What is RFC 2047?

RFC 2047 defines the encoded-word format used to place non-ASCII text inside email header fields.

What does =?UTF-8?B?...?= mean?

It means the header uses UTF-8 bytes and Base64 encoding. The encoded bytes can be decoded back into readable Unicode text.

What does =?UTF-8?Q?...?= mean?

It means the header uses UTF-8 bytes and Q encoding, where underscores often represent spaces and equals signs introduce hex byte values.

Is anything uploaded when I decode a header?

No. The decoder runs in your browser and does not send your pasted header text anywhere.