Free Base64 Decoder
Paste a Base64 string below to decode it back to plain text or download as a binary file. The tool detects whether the output is readable text or binary data automatically.
About Base64 Decoding
This Base64 decoder reverses Base64 encoding, converting the encoded string back to its original binary or text representation. It uses the browser's native atob() function for decoding and a TextDecoder for proper UTF-8 text output.
The decoder automatically detects whether the decoded bytes represent readable UTF-8 text or binary data, providing either a text preview or a file download accordingly.
Frequently Asked Questions
Yes. If you paste a data URI like data:image/png;base64,iVBOR..., the tool strips the prefix automatically and decodes the Base64 portion.
An error message is shown explaining the decoding failure. Common causes include missing padding (= characters at the end), invalid characters, or a truncated string.
Yes. The decoder automatically converts URL-safe Base64 (- and _) back to standard Base64 (+ and /) before decoding.
JWTs use Base64URL encoding for each segment. Use the dedicated JWT Decoder for a better experience with token inspection including header, payload, and expiry display.