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Base64 Encoding Explained: When and Why to Use It
Learn what Base64 encoding is, why it exists, when to use it, and common use cases in web development.
January 22, 2024·6 min read
What is Base64?
Base64 is an encoding scheme that converts binary data into an ASCII string format. It uses a set of 64 characters (A-Z, a-z, 0-9, +, /) to represent binary data.
Why Base64 Exists
Binary data can't be safely transmitted over channels designed for text. Base64 solves this by encoding binary data into text-safe ASCII characters.
Common Use Cases
1. Embedding Images in HTML/CSS
<img src="data:image/png;base64,iVBORw0KGgo..." />
2. JWT Tokens
JSON Web Tokens use Base64URL encoding for headers and payloads:
eyJhbGciOiJIUzI1NiJ9.eyJzdWIiOiIxMjM0In0.abc123
3. Email Attachments
MIME encoding uses Base64 for binary email attachments.
4. API Authentication
Basic HTTP Authentication uses Base64:
Authorization: Basic dXNlcm5hbWU6cGFzc3dvcmQ=
Base64 in JavaScript
// Encode
const encoded = btoa('Hello, World!')
// "SGVsbG8sIFdvcmxkIQ=="
// Decode
const decoded = atob('SGVsbG8sIFdvcmxkIQ==')
// "Hello, World!"
Base64 vs Base64URL
Base64URL replaces + with - and / with _ for URL safety.
Try our Base64 Encoder/Decoder tool for quick conversions.