What is Base64?

Base64 is an encoding scheme that represents binary data using 64 ASCII characters.

Why Base64?

Text-based protocols (email, XML, etc.) cannot natively handle binary data. Base64 converts binary into a safe, text-only format.

How It Works

Input bytes are split into 6-bit groups, each mapped to one of 64 characters (A-Z, a-z, 0-9, +, /).

Input: "Man"
Binary:   01001101 01100001 01101110
6-bit:    010011 010110 000101 101110
Base64:   T      W      F      u

Common Use Cases

• Email attachments: MIME encoding
• Data URIs: <img src="data:image/png;base64,...">
• JSON/REST APIs: embedding binary within JSON
• Auth headers: HTTP Basic Authentication

JavaScript

// Encode
const encoded = btoa('Hello, World!');
// "SGVsbG8sIFdvcmxkIQ=="

// Decode
const decoded = atob('SGVsbG8sIFdvcmxkIQ==');
// "Hello, World!"

Important Notes

• Base64 is not encryption — it can be decoded by anyone
• It increases data size by ~33%
• For URLs, use URL-safe Base64: replace + with - and / with _