Base64 Decoder
Decode Base64 and URL-safe Base64 to text with UTF-8 support. Clear errors for invalid characters, length and padding.
Processed locally in your browser. Your text is not uploaded.
What this tool does
Paste a Base64 string and read the text inside it. The decoder understands both the standard alphabet and the URL-safe one (- and _), works with or without = padding, and ignores line breaks and spaces, so strings copied from emails, config files, Kubernetes secrets or HTTP headers just work. A leading data:...;base64, prefix is stripped automatically.
Bytes are interpreted as UTF-8, so accented text, CJK characters and emoji come out correctly. If the data is not valid Base64, you get a specific message: an invalid character with its position, a length that cannot be Base64, or misplaced padding. If the data decodes but is not text, such as a PNG or a gzip stream, the tool says so instead of showing garbage.
Decoding runs locally in your browser. Be aware that Base64 is not encryption; decoded values like passwords or tokens remain sensitive.
How to use it
- 1Paste the Base64 string (standard or URL-safe, with or without padding).
- 2Read the decoded text in the output box, or fix the error described above it.
- 3Copy the result or download it as a text file.
Supported formats
Base64 or Base64url text in; UTF-8 text out. Binary payloads are detected and reported, not displayed.
Privacy
This tool runs in your browser. The data you provide is processed on your device and is not sent to our servers.
Limitations
- Only data that decodes to valid UTF-8 text can be displayed. Binary files (images, PDFs, archives) are reported as not text.
- Text in legacy encodings such as Latin-1 or Shift-JIS is not valid UTF-8 and will be reported as not text.
- A single stray character or a truncated string makes the whole input invalid; the decoder does not guess a repair.
- Very large inputs may be slow and memory-hungry in the browser.
FAQ
Why does it say the data is not UTF-8 text?
The Base64 itself is fine, but the bytes inside are not text in UTF-8: typically an image, a compressed file, encrypted bytes, or text in another encoding.
Can it decode URL-safe Base64 and JWT segments?
Yes. - and _ are accepted along with + and /, and missing padding is fine. For full tokens, the JWT Decoder splits and pretty-prints the parts for you.
What does “invalid length” mean?
Base64 text cannot have a length that leaves exactly one character over after groups of four. It usually means the string was cut off or has an extra character.
Is the decoded data uploaded?
No. Decoding is done in your browser.
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