Base64 - encodes binary data as ASCII text. Used for embedding images in HTML/CSS, email attachments, JWT tokens. Not encryption - anyone can decode it.
Base64URL - same as Base64 but URL-safe (uses - and _ instead of + and /). Used in JWTs and URLs.
URL Encoding - makes text safe to put in URLs. Spaces become %20, special chars become %xx.
Hex - represents bytes as hexadecimal. Used for binary data display, color codes (#ff5500), hashes.
Type in "Input", result appears in "Output". Toggle direction with Encode/Decode.