Base64 encoding is a method of converting binary data into ASCII text. It's widely used in web development for embedding data in URLs, HTML, CSS, and transmitting binary content over text-based protocols.

How Base64 Works

Base64 encoding converts every 3 bytes (24 bits) of binary data into 4 ASCII characters from a set of 64 characters:

Uppercase letters: A-Z (26)

Lowercase letters: a-z (26)

Digits: 0-9 (10)

Special characters: + and / (2)

Padding character: =

The encoding process:

Take 3 bytes of input (24 bits)

Split into 4 groups of 6 bits each

Map each 6-bit value to the Base64 character table

If input isn't divisible by 3, add padding (=)

Common Use Cases

Data URIs

Embed images directly in HTML/CSS:

Email Attachments

MIME encoding uses Base64 to include binary attachments in text-based email.

API Authentication

HTTP Basic Authentication sends credentials as Base64-encoded strings in the Authorization header.

JWT Tokens

JWT payloads are Base64URL-encoded (a URL-safe variant of Base64).

Base64 vs Encryption

Important: Base64 is NOT encryption. It's an encoding scheme — anyone can decode Base64 data. Never use Base64 alone to protect sensitive information.

URL-Safe Base64

Standard Base64 uses + and /, which have special meaning in URLs. URL-safe Base64 replaces these with - and _ respectively.

Try our Base64 Encoder/Decoder to encode and decode Base64 strings instantly.

Base64 Encoding Explained — Why and How It Works