Base64 File Encoder & Decoder
Encode a local binary or text file as plain Base64 or a Base64 Data URL entirely in your browser.
Select a file or switch to decoding. Processing stays in this browser.
Maximum file size: 5 MB. Encoded input is limited to 8 MB. Decoded files are never previewed, inspected, uploaded, or executed. (5 MB)
How to use it
- Choose encoding or decoding mode
- Select a local file for plain Base64 or Data URL output, or paste encoded input
- Review validated sizes and metadata before copying or downloading
- Clear the tool to remove the current file, bytes, and text from the interface
The tool reports the original filename, MIME type, input size, encoded payload size, and estimated expansion before allowing you to copy or download the encoded text. It can also decode pasted plain Base64 or a supported Data URL into downloadable bytes, using a filename and MIME hint that you control when metadata is absent. Strict validation rejects malformed padding, unsupported Data URL structures, oversized inputs, and unsafe filename characters. Decoded content is never previewed, inspected, uploaded, or executed. Temporary download URLs are revoked immediately, and conservative limits reduce avoidable memory pressure.
FAQ
Yes. Files are handled as bytes, within the stated size limit, without attempting to interpret their contents.
A supported Base64 Data URL supplies its MIME type; plain Base64 requires your own filename and MIME hint.
No. It is offered only as a download and is never previewed, executed, scanned, or uploaded.