What is a Base64 data URI?
Base64 turns binary data, like an image, into plain text made of letters, digits, +, / and padding =. A data URI wraps that text with a header (data:image/png;base64,) so a browser knows how to decode it. You can drop a data URI straight into an <img src>, a CSS background-image, or a JSON field, with no separate image file needed.
When to use it
- Embedding a small icon or logo directly in CSS or HTML, avoiding an extra network request.
- Sending an image inside JSON, for an API that doesn't accept file uploads.
- Pasting an inline image into an email template or a config file.
Base64 text is about 33% larger than the original file, so it suits small images (icons, small logos), not large photos.
Questions
Is my image uploaded anywhere?
No. The conversion happens with your browser's own Base64 encoder, and the "Base64 → Image" side decodes entirely on your device too.
Why does decoding say "this does not look like an image"?
Pasted text without a data:image/... header only decodes if the bytes match a known image signature (JPEG, PNG, WebP, GIF or BMP). If you have the header, paste the whole data URI instead.
Can I paste Base64 that's split across several lines?
Yes, line breaks and spaces are ignored when decoding.
Is it really free?
Yes. There is no sign-up, watermark or limit.