Base64 Encoder

Base64 turns arbitrary data into sixty-four characters that survive being sent as plain text. It is not encryption and it hides nothing — anyone can decode it instantly — but it is what lets a token travel in an HTTP header, an image sit inside a CSS file, or an attachment cross an email system that only understands text.

The part that trips people up is not Base64 itself but the encoding underneath it. The browser's built-in function works on bytes and refuses anything above the basic Latin range, so encoding a single accented letter throws an error, and the common workaround produces bytes that other languages decode into something different. This tool converts text to real UTF-8 first, so an emoji or a line of Hindi encodes to exactly what any correct implementation elsewhere would produce.

The URL-safe option swaps the two characters that cause trouble in links. Standard Base64 uses plus and slash, both of which have their own meaning inside a URL and have to be escaped; URL-safe Base64 uses hyphen and underscore instead and drops the trailing padding. If the result is going into a query string, a filename or a JWT, that is the variant you want.

Line wrapping at seventy-six characters is there for the older standards that require it, notably MIME email. Everything runs in the page, so a token or a key you are encoding never leaves your device.