What is a Base64 Data URI?

A Data URI (data:mime/type;base64,...) embeds the file contents directly in a URL. You can use it as an image src attribute to embed images in HTML without hosting them externally.

Can I convert large files?

Yes, but be aware that Base64 encoding increases file size by about 33%. Very large files (>10MB) may cause the browser to slow down. The tool processes files entirely in your browser - nothing is uploaded to a server.

File to Base64 Converter - Free Online Data URI Tool

Using the Online Data URI Tool

Drag and drop a file into the upload area, or click to browse.
The file is read by your browser's FileReader API - nothing is uploaded to any server.
Copy the Base64 string or the complete data URI (data:[type];base64,...).
Use the data URI directly in HTML img src, CSS background-image, or JSON payloads.

File to Base64 Converter is a secure way to transform binary data into a string of printable ASCII characters for embedding in web projects. This binary to base64 process is essential for creating data URIs, which allow you to include images, fonts, and PDFs directly in HTML or CSS files without external requests. This tool performs all encoding locally in your browser for maximum privacy.

Generating Base64 Image Strings

A data URI has the form data:[mediatype];[encoding],[data]. For a PNG image encoded in Base64: data:image/png;base64,iVBORw0KGgo.... This string can be used as a file encoder output for img src, CSS background-image, or JSON API payloads. This file to base64 process is highly efficient for small assets, though large files will result in significant Base64 string expansion.

Encodes any file type: images, fonts, PDFs, audio, binary executables
Outputs both raw Base64 and a complete data URI string
MIME type detected automatically from file extension
No file size limit - the browser holds the Base64 string in memory

Frequently Asked Questions

What types of files can I encode to Base64?

Any file. The tool reads raw bytes regardless of format. Images, PDFs, ZIP archives, fonts, audio files, and even binary executables all produce valid Base64 output.

Why is my Base64 string so long?

Base64 expands binary data by approximately 33% - every 3 bytes become 4 characters. A 100 KB image produces about 133,000 Base64 characters. Data URIs over ~5–10 KB can noticeably affect page load performance.

How do I use a Base64 image in CSS?

Use the data URI directly in the CSS: background-image: url("data:image/png;base64,...");. This embeds the image directly in the stylesheet, saving an HTTP request - useful for small repeating patterns and icons.

Can I decode a Base64 string back to a file?

Yes - use the Base64 Encoder tool in Decode mode, paste the Base64 string, and download the resulting binary. The data URI prefix is stripped automatically before decoding.

Try our Base64 Encoder, ASCII85 encoder, or HTML Formatter for more developer tasks. Bookmark this File to Base64 Converter for all your data URI needs.

File to Base64 Converter online

Convert any file to Base64 and generate a Data URI - runs entirely in your browser

Why is the Base64 output larger than the original file?

Can I use the Base64 output directly in HTML?