Base64 Decoder
Decode Base64 or a data URI back to text or a downloadable file. Invalid input is reported clearly — decoding runs in your browser.
Base64 Decoder
Decode Base64 or a data URI back to text or the original file.
How to use
The whole flow runs in your browser — nothing is uploaded.
- Paste Base64A raw payload or a full data: URI — whitespace and line breaks are ignored.
- DecodeValid input is decoded instantly; invalid characters are reported.
- Check the resultText output and file size, plus the MIME type recovered from a data URI header.
- ExportCopy the text, or download the reconstructed file.
- Every step runs locally in your browser.
Key Features
Decode Base64 back to readable text or a downloadable file. Everything runs client-side on your own device.
- UTF-8 decodingMulti-byte characters decode correctly — no mojibake.
- Clear invalid-input messagesIllegal characters, wrong length and padding problems are explained.
- File recoveryDownload the decoded bytes with the extension that matches their MIME type.
- No uploadDecoding is done in your browser.
Frequently asked questions
Characters outside the Base64 alphabet, a length that cannot be a valid group of four, or incorrect padding. The tool tells you which one it found.
Yes. Paste the whole data:... URI and the prefix is stripped automatically; the MIME type is used to name the downloaded file.
Binary data decoded as text produces unreadable characters. Use the file output instead when you are decoding images, archives or documents.