Base64 Encoding Explained — What It Is, How It Works & When to Use It

Published August 2026 · 6 min read

What is Base64?

Base64 converts binary data into a text-safe alphabet of 64 characters (A–Z, a–z, 0–9, +, /). It exists because many protocols (email, JSON, URLs) were designed for text, not raw bytes.

How It Works

Every 3 bytes (24 bits) become 4 Base64 characters (6 bits each). If input isn't divisible by 3, = padding is added.

"Hi" → bytes [72, 105] → bits 010010 000110 1001xx → "SGk="

Common Uses

• Data URIs: inline images without extra HTTP requests
• API auth: Basic Auth headers (Authorization: Basic dXNlcjpwYXNz)
• JWT tokens: header.payload.signature segments (see our JWT Decoder)
• Email attachments: MIME encoding

⚠️ Base64 Is NOT Encryption

Any Base64 string decodes instantly. Never encode secrets thinking they're protected — it's obfuscation at best. For real security use hashing or proper encryption.

Try It

Use our Base64 Encoder/Decoder — runs entirely in your browser, nothing is uploaded.

FAQ