File to Base64 Converter (Data URI)

Base64 turns any file into plain text so it can travel inside JSON, HTML, CSS, e-mail or configuration files. This converter reads files in your browser and writes them as raw Base64, as a data URI with the right MIME type, as unpadded Base64URL, or wrapped at 64 or 76 characters for PEM and MIME, with optional CSS, HTML and JSON snippets. Several files can be converted at once.

How to use this tool

1. Choose one or more files.
2. Pick the output form: a data URI to embed in a page, raw Base64 for APIs, or wrapped lines for PEM and e-mail.
3. Optionally choose a snippet such as an <img> tag or a CSS url().
4. Copy the text, or download it when it is too long to display.

Formula

Base64 length = 4 × ⌈bytes ÷ 3⌉ characters; a data URI adds "data:" + MIME type + ";base64,".

Every 3 bytes become 4 characters from A–Z, a–z, 0–9, + and /, with = padding at the end. Base64URL uses - and _ instead of + and / and drops the padding, so it is safe in URLs and file names.

Example

The 26-byte text file "Hello world.\nSecond line.\n" becomes SGVsbG8gd29ybGQuClNlY29uZCBsaW5lLgo= — 36 characters, 38.5% larger — and as a data URI data:text/plain;base64,SGVsbG8gd29y…Lgo=.