What this does
Encodes text or a file into Base64 or Base64URL. Base64 turns arbitrary bytes into a string made of letters, digits, and a few symbols, so the data can travel safely through text-only channels like JSON fields, URLs, or email.
Base64 vs Base64URL
Standard base64 uses + and / and pads with =. Base64URL replaces those with - and _ and drops padding, so the result can be used directly inside a URL or filename without extra escaping.
Privacy
This runs entirely in your browser. Nothing is uploaded.