Base64 Encoding Explained - What It Is and How to Use It

What is Base64 Encoding?

Base64 is a binary-to-text encoding scheme that represents binary data in an ASCII string format. It converts binary data into a set of 64 characters (A-Z, a-z, 0-9, +, /) that can be safely transmitted over text-based protocols.

Why Use Base64?

• Email attachments: MIME uses Base64 to encode binary files in emails
• Data URIs: Embed images directly in HTML/CSS
• API authentication: HTTP Basic Auth encodes credentials in Base64
• JWT tokens: JSON Web Tokens use Base64URL encoding
• Configuration files: Safely store binary data in text files

How Base64 Works

1. Take the binary data (e.g., text converted to ASCII bytes)
2. Split into groups of 6 bits (instead of the usual 8)
3. Map each 6-bit group to one of 64 characters
4. Add padding (=) if the data doesn't divide evenly

Example

Text: Hi → ASCII: 72 105 → Binary: 01001000 01101001

Split into 6-bit groups: 010010 000110 1001xx

Map to Base64: S G k + padding = → Result: SGk=

Common Use Cases

Encoding an Image for HTML

<img src="data:image/png;base64,iVBORw0KGgo..." />

HTTP Basic Authentication

Authorization: Basic dXNlcm5hbWU6cGFzc3dvcmQ=

Storing Binary Data in JSON

{
  "file": "SGVsbG8gV29ybGQ=",
  "filename": "hello.txt"
}

Base64 vs Encryption

Important: Base64 is not encryption. It's encoding — anyone can decode it. Never use Base64 alone to protect sensitive data.

Try It Now

Use our free Base64 encoder/decoder to encode or decode Base64 strings instantly!