Base64 Encode / Decode

Base64 encodes binary data into a text-safe format using 64 ASCII characters: A-Z, a-z, 0-9, +, and /. It's used whenever binary data needs to travel through text-only channels — email attachments (MIME), data URIs in CSS/HTML, JSON payloads, and API authentication headers.

The encoding works by taking 3 bytes (24 bits) of input and splitting them into 4 groups of 6 bits, each mapped to one of the 64 characters. This means Base64 output is roughly 33% larger than the original data. The = padding character fills in when the input length isn't divisible by 3.

URL-safe Base64 replaces + with - and / with _ to avoid conflicts with URL query parameters. This tool supports both standard and URL-safe variants, and processes everything client-side using the browser's btoa() and atob() functions.