Base64 writes file bytes as text so you can transport them in a text-only field. It is an encoding, not encryption. Base64 File reads a selected file in the browser and can turn encoded text back into a download.
Decode a known example
Paste SGVsbG8= into Base64 → File and choose Decode to file. The status should say 5 bytes ready, and a Download file link appears. Download it: the default name is decoded.bin, and its contents are Hello. The .bin extension is used because bare Base64 has no filename or file-type information. An invalid string instead shows a decoding error; correct the input and try again.
Encode your own small test file
Create a plain-text file containing exactly Hello (no trailing newline). Choose it under File → Base64 and press Encode file. Base64 should show SGVsbG8=. Enable Include the data URL prefix, then encode again; the output also includes a data: header and a comma before the Base64 text. That header records the browser-reported file type. Copy and Download text save the text, not the original file.
The tool processes file bytes in this tab. Avoid copying sensitive file contents into tickets or shared chats; anyone can decode Base64. Large files create even larger text output and use browser memory.
Where your input goes
Processing runs in your browser. The tool does not upload your input to ilham.dev.
Related guide
For more background, read Browser File Tools.
Questions you might have
- Is there a size limit?
- Whatever your browser can hold in memory. Base64 inflates a file by about a third, so a 3 MB image becomes roughly 4 MB of text.
- Should I embed images as data URIs?
- Only for small files. A data URI cannot be cached separately from the stylesheet it lives in and it has to be parsed along with it, so anything past a few kilobytes is usually better served as an ordinary file.