Base64 Decode
Decode Base64 strings back to UTF-8 text in your browser. Handles padding and whitespace automatically.
Base64 decoding reverses the encoding process, turning ASCII-safe text back into its original bytes. It is essential when inspecting API responses, reading embedded data URLs, or debugging authentication headers.
The decoder is forgiving about padding and line breaks, but it will reject characters outside the Base64 alphabet so that genuinely corrupt input is surfaced rather than silently mangled.
The decoder ignores line breaks and spaces, so you can paste a PEM block or a JSON string directly without pre-cleaning it.
Common uses
- Inspecting the payload of a JWT, a SAML assertion, or a Docker config that stores credentials as Base64.
- Extracting the original text or binary from a data URL embedded in HTML or CSS.
Frequently asked questions
- Why does my decoded output look garbled?
- The input was probably not valid UTF-8 before encoding, or it was double-encoded. Check that you are decoding only one layer.
- Do I need the padding equals signs?
- Standard Base64 requires padding to a multiple of 4 characters, but this decoder tolerates missing padding and also ignores whitespace.
- Is decoding Base64 safe?
- Decoding itself is safe—it just reveals the original data. The risk is in what you do with the decoded content, since Base64 often wraps credentials or tokens.
- What characters are allowed?
- Only A-Z, a-z, 0-9, '+', '/', and '=' for padding. Anything else is rejected so corruption is visible instead of silent.
- What happens with invalid input?
- Characters outside the Base64 alphabet are rejected with an error, so corrupted input is surfaced instead of silently producing wrong output.