Encoding
Base64 Decode
Paste Base64 text and decode it locally, with validation for malformed input and Unicode-safe output.
Runs locally in your browser. Your input is not uploaded. Base64 is encoding, not encryption.
How this tool works
Base64 decoding converts text-safe encoded bytes back into readable text when the bytes represent valid Unicode.
Malformed input is reported so you can fix padding or invalid characters.
Examples
- Decode a sample API value.
- Inspect the text inside a Base64-encoded configuration string.
- Decode an emoji payload with UTF-8 and verify the same characters are recovered.
Common use cases
Decoding with context
Base64 decoding turns encoded text back into bytes and then readable Unicode text when the bytes represent text. If the original data was binary, the result may not display as useful text.
Decoded values can contain secrets, configuration, or tokens. Treat the output with the same care you would give the original data.
Invalid or unsafe assumption
Invalid/failure example
SGVsbG8$ contains a character outside the standard Base64 alphabet.
Mistakes to avoid
- Silently accepting invalid alphabet characters.
- Assuming decoded bytes are always UTF-8 text.
- Executing or opening decoded content without inspection.
Limits of this workflow
Text preview requires valid UTF-8.
Arbitrary decoded bytes should be treated as untrusted file content.
Local-processing and privacy boundary
Decoding and byte download run locally; sensitive credentials remain sensitive after decoding.
Practical workflow
- Validate alphabet and padding.
- Decode bytes.
- Use UTF-8 preview only when appropriate.
- Inspect untrusted output before opening it elsewhere.
Related guides
Official references
FAQ
What happens with invalid Base64?
The tool shows an error instead of returning partial or misleading output.
Can Base64 contain secrets?
Yes. Treat decoded values carefully because Base64 is not encryption.
Why can valid Base64 fail as text?
Base64 can represent any bytes, while the text preview requires those bytes to form valid UTF-8.