Learn Base64

Short, practical guides - read one in five minutes, then try it in the tools.

What is Base64 and how does it work?

A clear explanation of Base64 encoding: the 64-character alphabet, how 3 bytes become 4 characters, padding, size overhead, URL-safe Base64 and when (not) to use it.

Base64 encode and decode in every language

Copy-paste examples to encode and decode Base64 (and Base64URL) in Java, JavaScript (browser and Node.js), Python, C#, Go, PHP, Bash and SQL.

Data URIs: embedding files in HTML and CSS

How data URIs work, the exact syntax, when embedding images as Base64 makes pages faster or slower, SVG without Base64, and size limits.