Base64 Encoder & Decoder

What is Base64?

Base64 is a binary-to-text encoding scheme that represents binary data using a set of 64 ASCII characters: A-Z, a-z, 0-9, +, and /. The = character is used for padding when the input length is not divisible by 3.

Base64 encoding increases the data size by approximately 33% — every 3 bytes of input become 4 characters of output. Despite the size increase, it is invaluable when binary data needs to travel through text-only channels.

Common Use Cases

• Data URIs: Embedding small images or fonts directly in HTML or CSS using data:image/png;base64,...
• Email (MIME): Email attachments are encoded in Base64 so they can travel through text-based email protocols
• JSON Web Tokens (JWT): The header and payload of a JWT are Base64url-encoded
• API payloads: Sending binary data (files, images) in JSON API requests
• Basic HTTP Authentication: Credentials are sent as a Base64-encoded username:password string

Base64 Encoding Table

The 64 characters in standard Base64 are: A-Z (0-25), a-z (26-51), 0-9 (52-61), + (62), / (63). Each character represents 6 bits of data. Three input bytes (24 bits) map to four Base64 characters (24 bits).

Base64 vs Encryption

Base64 is not encryption. It is a reversible encoding that provides no security. Anyone can decode a Base64 string without any key. Do not use Base64 to "protect" sensitive data — use proper encryption algorithms (AES, RSA) for that purpose.

Frequently Asked Questions