Base64 Decoder
Paste a Base64 text value and decode it to UTF-8 without uploading or treating arbitrary binary data as text.
A QUICK WALKTHROUGH
How to use this tool
- Paste standard Base64 up to 100,000 characters.
- Choose Decode Base64.
- Review the UTF-8 text and copy it if needed.
Strict UTF-8 text boundary
Only standard Base64 characters are accepted. Whitespace is rejected, padding must be valid, decoded bytes must be valid UTF-8, and input is limited to 100,000 characters. This tool decodes text; it is not an arbitrary binary-file decoder or file previewer.
Local and not encryption
Decoding runs in this browser with TextDecoder. Nothing is uploaded or stored. Base64 is an encoding, not encryption; decoded text may contain sensitive information.
GOOD TO KNOW
Common questions
Why is my input rejected?
Check for non-Base64 characters, whitespace, incorrect padding, a length that cannot form complete groups, or bytes that are not valid UTF-8.
Can it decode any binary file?
No. It only returns valid UTF-8 text. Use a format-specific binary tool when the decoded bytes are not text.
Does Base64 protect secrets?
No. Anyone with the value can decode it. Do not use Base64 as encryption.