Free Base64 Encoder & Decoder

Questions and answers

Is my data sent anywhere?

No. Encoding and decoding run entirely in your browser. Nothing leaves your device, no server is involved, and no analytics see your input.

What's the difference between standard and base64url?

URL-safe (base64url) replaces + and / with - and _, and often omits the trailing = padding. It's the variant used by JWTs, signed cookies, and URL query parameters where reserved characters would otherwise need escaping.

Why do my emoji break in other online base64 tools?

Most online tools use the browser's raw btoa() function, which only handles Latin-1 characters. We use TextEncoder so Unicode (emoji, CJK, RTL scripts) round-trips correctly.

Can I encode files?

Yes. Switch the source tab to File and drop a file into the input pane (or click to pick one). Up to about 100 MB.

What's a data URL?

A data URL is the inline format data:<mime>;base64,<content> used to embed a file directly in HTML or CSS without a separate network request. Toggle the "data URL" checkbox in the output pane (file mode only) to wrap the encoded bytes in this format.

What is the file size limit?

Soft warning at 10 MB; hard cap at 100 MB. Past that, the browser starts choking on the large in-memory strings that base64 encoding produces (a 100 MB file becomes a 133 MB base64 string).