🧠 Quoted-Printable & Base64 Decoder
Instantly decode MIME-encoded email content — paste and get clean, readable output in your browser. No sign-up, no data stored.
The Comprehensive Guide to MIME Encodings (RFC 2045)
In the architecture of modern email, the MIME (Multipurpose Internet Mail Extensions) standard defines how content is transformed for reliable transmission across different networking protocols. While the headers use RFC 2047 for short segments like subjects, the email body relies on RFC 2045 for larger blocks of text or binary data.
Our HTML Decoder provides a secure, client-side environment to reverse these encodings, allowing you to inspect raw email sources, debug rendering issues, or extract content from legacy systems without exposing your data to external servers.
📧 Quoted-Printable (QP)
Best for text-heavy bodies. It encodes non-ASCII characters as =XX (Hex) while keeping standard English letters readable. It also handles line length restrictions via "soft line breaks" (an = at the end of a line).
🔐 Base64 Encoding
The standard for binary data (images, attachments) or full HTML bodies. It converts data into a secure 64-character alphabet, increasing the size by approximately 33% but ensuring 100% data integrity.
📜 MIME Compliance
Our decoder is fully compliant with RFC 2045, the foundation of modern email communication, ensuring that even complex nested MIME structures can be decoded accurately.
Decoding Quoted-Printable Text
Quoted-Printable is often used when a document consists largely of characters that are already printable. For example, the character "é" is represented as =C3=A9 in UTF-8. Our tool automatically handles these multi-byte sequences to deliver perfect human-readable text.
Case Study: Email developers often see =20 (space) or =3D (equals sign) in their raw code. These are artifacts of QP encoding used to prevent character corruption during SMTP transmission.
How Base64 Works
Base64 takes 3 bytes of data and represents them as 4 characters from its 64-character set. This makes it ideal for transmitting binary files over systems designed only for text. If the input data isn't a multiple of 3, the output is "padded" with = or == characters at the end—a hallmark of the Base64 algorithm.
Frequently Asked Questions (FAQ)
Why is my email body encoded?
Email protocols (SMTP) were originally designed for plain text. Any CSS, HTML, or international characters must be encoded to ensure they aren't mangled by older mail servers.
Can I decode images using this tool?
While this tool is optimized for text/HTML decoding, it will technically decode the raw bytes of a Base64 image. However, it is primarily intended for inspecting the markup of HTML emails.
Where can I find the "Raw" email content?
In Gmail, click the three dots on an email and select "Show original." In Outlook, select "View message source." Look for the Content-Transfer-Encoding header to see which method was used.