Base64 File Encoder & Decoder
Encode any file (≤10 MB) to Base64 or a data: URI, or paste Base64 to decode it back to a downloadable file. Drag-and-drop, URL-safe alphabet supported.
Quick answer: Encode any file (≤10 MB) to Base64 or a data: URI, or paste Base64 to decode it back to a downloadable file. Drag-and-drop, URL-safe alphabet supported.
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Frequently asked questions
- How do I Base64 encode a file?
- On the Encode tab, drop a file (max 10 MB) and the Base64 string appears immediately. One click copies it to the clipboard.
- How do I decode Base64 back to a file?
- Switch to the Decode tab, paste the Base64 (plain or a `data:` URI), pick a filename, and click Download — your browser saves the original bytes.
- Why is there a 10 MB limit?
- Base64 inflates files ~33% and copying very long strings can hang the browser. 10 MB is the safe ceiling for both encode and decode.
- What does URL-safe mean?
- Replaces `+` with `-`, `/` with `_`, and drops trailing `=` so the string is safe in URLs and JWTs. The decoder accepts both alphabets.
- What is a data: URI?
- A self-contained URL like `data:image/png;base64,...` you can paste straight into <img src> or CSS background:url(). The decoder also reads these and reuses the MIME type.
- Does the file leave my device?
- No. Reading, encoding and decoding happen entirely in your browser — nothing is uploaded.
- What MIME type is used?
- Encode uses the type your OS reports for the file (or `application/octet-stream`). Decode reuses the MIME type from a data: URI when present.
- Why is my Base64 huge?
- Base64 grows raw bytes by about a third. For images, prefer compression (try Compress Image) before encoding.
- Can I encode files on mobile?
- Yes. Drag-and-drop becomes a file picker on phones, and decode works the same way.
- Is this Base64 file encoder free?
- Yes — free, no signup, no limits.