Base64 Decoder

What this decoder does

Paste a Base64 string and the tool converts it back to readable text. After decoding the bytes it interprets them as UTF-8, so accented characters and non-English text come out correctly rather than as garbled symbols. The work happens in your browser; the string is not uploaded.

Examples

• SGVsbG8gV29ybGQ= decodes to Hello World.
• Y2Fmw6k= decodes to café.
• dXNlcjpwYXNzd29yZA== decodes to user:password, the kind of value found in an HTTP Basic authentication header, which is a good reminder that Base64 gives no secrecy.

When decoding fails

1. Stray characters. Spaces, quotes or a prefix such as Basic or data:image/png;base64, must be removed first.
2. URL-safe input. Strings containing - or _ use the URL-safe alphabet. Replace - with + and _ with / before decoding.
3. Wrong length. A valid string's length is a multiple of 4 once padding is included. Truncated copies are a very common cause of errors.
4. Binary content. If the string represents an image, PDF or other binary file, the text view will show unreadable characters. That does not mean decoding failed; the data simply is not text.

Security reminders

• Decoded data can be anything. Do not run or open content that you do not recognise.
• Credentials found in decoded strings are fully exposed. If you find real secrets in a config or log file, rotate them.
• Base64 is encoding, not encryption. If a system relies on it for protection, it provides none.

Related tools

Use the Base64 encoder for the opposite direction, the JWT decoder for tokens, and the URL encoder for percent-encoding.