What this tool does
The decoder first checks the Base64 characters, length and padding, then calls atob to get the bytes, and finally uses the fatal mode TextDecoder to decode UTF-8. This will not silently replace invalid bytes into garbled characters.
- Ordinary whitespace added during copying can be ignored.
- Targets UTF-8 text only; arbitrary binary files are not suitable for text output.
- Exceptions will be caught and will not crash the entire page.
How to use it
- Paste the Base64 string.
- Click "Base64 Decode".
- If the input is valid, view the recovered Unicode text.
- Copy the desired results.
Common uses
- View the Base64 text value in the configuration.
- Validate encoding roundtrips for Chinese, Japanese, and emoji.
- Troubleshoot incorrect padding or non-UTF-8 data.
Base64 Decode Features
Recover multilingual Unicode text by strictly checking Base64 and then decoding it as UTF-8. It is suitable for daily development, debugging, data sorting and code optimization scenarios. The processing results can be directly viewed, copied or downloaded.
FAQ
Why can some Base64 decode into bytes but still report an error?
It may not be UTF-8 text. This page uses strict UTF-8 decoding to avoid displaying any binary as corrupted characters.
Is it possible to input Base64 with line breaks?
Yes, the tool will remove common whitespace before validating.
How to deal with invalid padding?
Invalid Base64 is displayed when the character position or = padding does not comply with the rules, and no unhandled exception is thrown.