File to Base64 Converter Online - Any File Type

This one takes any file at all. Zip, docx, xlsx, csv, json, fonts, video, even files with an extension nobody recognises. It reads raw bytes, so the format does not matter.

You get two blocks back: the data URI with its MIME type, and the raw Base64 string with no prefix. Your browser does the work, so nothing is uploaded.

How to Convert a File to Base64

1. Click Select File and pick anything.
2. Both output blocks appear underneath.
3. Copy the one you need, or download it as a .txt file.

Which File to Base64 Output to Use

Picking the wrong one is the most common reason a string gets rejected downstream.

1. With MIME type - starts with data: then the type, then ;base64,. Use this in HTML, CSS, or anywhere a browser reads it.
2. Raw string only - just the characters. Use this for JSON fields, API bodies, config files and database columns.

If an API returns a decode error, check this first. Nine times out of ten a data URI was sent where raw characters were expected.

What the MIME Type Tells You

Your browser guesses the type from the file extension. A few you will see often:

1. application/zip - zip archives
2. application/vnd.openxmlformats-officedocument.wordprocessingml.document - docx
3. text/csv - spreadsheet exports
4. font/woff2 - web fonts
5. application/octet-stream - the fallback when the extension is unknown

Seeing octet-stream is fine. It just means the browser could not name the format, and the bytes are encoded correctly either way.

Your File Never Leaves Your Device

Most converters send your file to a server, encode it there, and return the text. This page does the opposite. The file is read on your own machine with the browser FileReader API and never goes over the network.

That matters when the file is a database dump, a signed document, a private key, or a client archive. No upload, no stored copy, no account.

Size Is the Thing to Watch

Base64 turns 3 bytes into 4 characters, so the string runs about 33% bigger than the file. A 3 MB zip becomes about 4 MB of text.

There is no cap here because your device does the work, but a very large file will make the tab slow while it encodes and awkward to paste anywhere afterwards.

Format-Specific Pages

If you know your file type, the dedicated pages give you better snippets. PDF to Base64 adds an iframe embed, and image to Base64 adds an img tag and a CSS rule.

For plain writing rather than a file, text to Base64 encodes what you type straight into the box.