Base64 Encode and Decode

No. Pasted text and dropped files are both read and converted entirely on your device, and nothing is sent to a server. Turn off your Wi-Fi after the page loads and it still works. This page loads 11KB of JavaScript, gzipped - about what your browser's network tab will show for this page's own scripts.

A way of representing arbitrary bytes (any file, or text with characters outside plain ASCII) using only 64 printable characters - letters, digits, +, and /. It is not encryption and does not hide or protect data; anyone can decode it back to the original with a tool like this one.

Yes. Drop any file to encode - a common use is turning a small image into a Base64 string to embed directly in CSS or HTML. In decode mode, drop a text file that contains Base64 and download the decoded result as a binary file.

Standard Base64 uses + and /, both of which have special meaning inside a URL. URL-safe Base64 (RFC 4648 section 5) swaps those two characters for - and _ instead, so the result can be dropped straight into a URL or filename. Turn the toggle on if the Base64 you are working with came from a URL, a JWT, or an API that documents itself as URL-safe.

The result is checked to see whether it is valid UTF-8 text. If it is not (almost always genuine binary data, such as an image or a PDF), you get a plain message saying so and a download button for the decoded file, rather than a garbled attempt to display it as text.

You get a plain-English message naming the specific problem - a character outside the Base64 alphabet, padding in the wrong place, or a length that is not possible for Base64 - instead of a silent wrong result. Whitespace and line breaks in the pasted text are ignored rather than treated as errors, since that is how Base64 is often shared.