Base64 is a binary-to-text encoding scheme that converts binary data into an ASCII string using 64 characters (A–Z, a–z, 0–9, +, /). It takes 3 bytes of input and produces 4 characters of output, making the encoded result roughly 33% larger than the original.

Common use cases include data URIs (embedding small images or files directly in HTML/CSS), email attachments (MIME encoding for binary content in email), API credentials (Basic Auth sends username:password as Base64), and embedding images in HTML/CSS (data:image/png;base64,…).

URL-safe Base64 replaces + with - and / with _, and strips = padding — making the output safe to use in URLs, query parameters, and filenames without additional escaping. This tool runs entirely in your browser — your data never leaves your device.