What is Base64 and when should you use it?

Many systems, such as email and JSON, are designed for plain text and can break or corrupt raw binary data. Base64 represents any bytes using just 64 safe characters: A–Z, a–z, 0–9, + and /.

Three bytes (24 bits) are split into four 6-bit groups, each mapped to one character. Padding with = fills the end when the input length is not a multiple of three.

Base64 appears in data URLs for small images, email attachments, HTTP basic authentication headers and the segments of JSON Web Tokens. A URL-safe variant uses - and _ instead of + and /.

Because it turns 3 bytes into 4 characters, the output is about 33% larger than the input.

Anyone can decode Base64 instantly, so it provides no secrecy. Never use it to hide passwords, API keys or personal data.

If you need to protect information, use real encryption. Use Base64 only to transport data safely through text-based systems.

Browsers' built-in btoa function fails on characters outside Latin-1, such as emoji. The reliable approach is to convert the text to UTF-8 bytes first and then encode those bytes.

Our Base64 tool does this for you and decodes back to the original text in the same way.