Base64 Encode / Decode

Base64 Encode and Decode Online

This free Base64 encoder and decoder converts plain text to Base64 and Base64 back to readable text instantly, right in your browser. Paste your data, pick Encode or Decode, and the result updates while you type. Nothing is uploaded to a server, so it's safe to use with configuration files, tokens, and other private data.

How Base64 works

Base64 splits the input into groups of 3 bytes (24 bits) and maps every 6 bits to one of 64 printable characters: A–Z, a–z, 0–9, + and /. When the input length isn't a multiple of three, the output is padded with one or two = characters. The text is converted to UTF-8 bytes first, so accented letters, Turkish characters, Chinese text, and emoji are encoded correctly — something the browser's built-in btoa() function can't do on its own.

Options

• URL-safe – use the Base64URL alphabet (- and _) for URLs, cookies, and JSON Web Tokens.
• Padding – keep or drop the trailing = characters.
• Line wrap – break the output every 76 characters (MIME / email) or 64 characters (PEM certificates and keys).
• Decode as – read the decoded bytes as UTF-8 or Latin-1.

The decoder is forgiving: it ignores spaces and line breaks, accepts missing padding, understands both the standard and URL-safe alphabets, and strips a data:...;base64, prefix automatically. If the input contains an invalid character, you'll see its exact position.

Common uses

Developers use Base64 to embed small files in HTML and CSS, send binary attachments in email (MIME), store binary values in JSON or XML, pass data in URLs, read HTTP Basic Authentication headers, and inspect the header and payload of JWT tokens. For specific formats, try JSON to Base64, Image to Base64, or Base32 Encode / Decode.