Question 1

Does this handle non-English text correctly?

Accepted Answer

Yes. Text is encoded via TextEncoder/TextDecoder before Base64 conversion, so multi-byte UTF-8 characters (accents, Korean, emoji, etc.) round-trip correctly — a naive btoa()/atob() call would corrupt them.

Question 2

What is 'URL-safe' Base64?

Accepted Answer

Standard Base64 uses + and / characters, which have special meaning inside a URL. The URL-safe variant swaps those for - and _ instead (and often drops padding), so the result can be used directly inside a URL or filename.

Question 3

Can I convert a file to Base64?

Accepted Answer

Yes — drop a file onto the encoder and it's read directly into your browser's memory and converted to a Base64 data URI. The file is never uploaded anywhere.

Question 4

Why did decoding fail?

Accepted Answer

The input isn't valid Base64 for the mode you've selected — check you haven't mixed the standard and URL-safe character sets, and that the string length is a multiple of 4 once padding is accounted for.

Base64 Encode & Decode

Frequently asked questions