Base64 File Encoder
ConverterEncode any local file to a Base64 data URL for images, PDFs and binary files to embed assets directly in HTML, CSS, JSON and email attachment strings.
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About Base64 File Encoder
Embedding an image in CSS, sending an attachment as a data URI, or carrying a small file inside JSON all require encoding a binary file as Base64 text. This tool encodes files (images, PDFs, fonts, and more) into Base64 strings locally in your browser, and decodes Base64 back into a downloadable file, optionally producing a data URI with the MIME type. Files never leave the browser or reach a server, so even sensitive documents are safe.
How to Use
- Open the Base64 File Encoder tool
- Select the source and target formats
- Adjust the output options as needed
- Click the Convert button; results appear in real time
- Copy or export the result
Use Cases
- Inline icons — Encode a small icon as a data URI to drop into CSS and save an HTTP request.
- Email attachments — Convert a file to Base64 to embed in an email or an API JSON field.
- Restore files — Decode a Base64 string from an API and download it as the original image or PDF.
- Inline configs — Encode a certificate or font to embed in config and ship with the program.
- Quick inspection — Decode an unknown Base64 blob to find out whether it is an image, text, or other file.
- Favicon generation — Encode a small PNG or SVG as a Base64 data URI to embed inline in HTML for a zero-request favicon.
- API response inspection — Decode a Base64 file from an API response to verify the returned image, PDF, or binary matches expectations.
FAQ
Does Base64 make files bigger?
Yes. Base64 uses 4 characters per 3 bytes, growing size by about 33%. In return you can move binary safely through text-only channels — best for small files, not large ones.
How does a data URI differ from raw Base64?
A data URI prepends data:type;base64, so browsers render it directly; raw Base64 is just the encoded string and needs the type communicated separately.
How large a file can it handle?
Encoding happens in browser memory, so a few MB is fine, but tens of MB can get slow or stutter. Use a CLI tool for large files.
How do I know the file type when decoding?
If the source is a data URI with a MIME type, the tool uses it; for raw Base64 you may need to set the extension manually to download correctly.
Can line breaks or spaces break decoding?
Standard Base64 is sometimes line-wrapped. The tool usually ignores whitespace before decoding, but a truncated string or non-Base64 characters will fail.