Base64 File Converter — Free Online
Convert files to Base64 and Base64 back to files with this free online tool. Supports images, PDFs, and any binary file. No sign-up required.
Drop a file here or click to upload
What is Base64 File Encoding?
Base64 file encoding converts any binary file — images, PDFs, audio, executables — into a plain-text ASCII string using the Base64 alphabet (A-Z, a-z, 0-9, +, /). This is especially useful when you need to embed binary content in text-only formats such as JSON payloads, HTML data URIs, CSS backgrounds, or email attachments. A data URI combines the MIME type with the Base64 string (e.g. data:image/png;base64,iVBOR...) so browsers can render the file directly from the string without an extra HTTP request.
How to Use This Free Online Base64 File Converter
- Choose a mode: 'File → Base64' to encode, or 'Base64 → File' to decode.
- To encode: drag and drop a file or click to upload. The Base64 output appears instantly.
- Toggle 'Include data URI prefix' on or off depending on whether you need the full data URI or raw Base64.
- Click the Copy button to copy the result to your clipboard.
- To decode: paste a Base64 string (with or without the data URI prefix) and click Download File.
Common Use Cases for Base64 File Conversion
- Embedding images in HTML or CSS — Convert small icons and logos to data URIs so they load inline without additional HTTP requests, improving page performance.
- Sending files through JSON APIs — Many REST APIs accept file uploads as Base64-encoded strings inside JSON bodies, avoiding multipart form handling.
- Storing files in text-based databases — Some NoSQL or configuration stores only accept text values. Base64 lets you persist binary data safely.
- Email attachment encoding — MIME email standards encode binary attachments as Base64 so they can travel through text-only email transport layers.
FAQ
What file types can I convert to Base64?
Any file type works — images (PNG, JPG, GIF, SVG, WebP), PDFs, audio files, videos, ZIP archives, and more. Base64 encoding is format-agnostic; it simply converts raw bytes to text.
Why is the Base64 output larger than the original file?
Base64 encoding increases size by approximately 33% because it maps every 3 bytes to 4 ASCII characters. For large files, consider using direct binary transfer instead.
Is my file uploaded to a server?
No. All conversion happens entirely in your browser using the JavaScript FileReader API. Your files never leave your device.
What is a data URI prefix?
A data URI (e.g. data:image/png;base64,...) embeds the MIME type alongside the Base64 string so browsers know how to interpret the data. It's required for inline images in HTML/CSS but not needed for API payloads.