Base64 is one of those things developers use constantly — in JWTs, data URLs, API authentication — without always understanding what it actually does. Here's a clear explanation.

What Base64 is (and isn't)

Base64 is an encoding scheme , not encryption. It converts binary data into a string of 64 printable ASCII characters: A-Z , a-z , 0-9 , + , and / , plus = for padding.

The purpose: safely represent binary data in contexts that only handle text. Email attachments, HTML data URLs, and HTTP headers are all text-based — Base64 lets you embed binary content (images, files) in those contexts without corruption.

If you need to encode or decode Base64 in the browser, the Base64 Encoder/Decoder handles both directions instantly.

How it works

Base64 works in three steps:

Take the binary input as bytes (8 bits each)

Group the bits into 6-bit chunks

Map each 6-bit value (0–63) to one of the 64 characters

Example with "Man":

M = 01001101 a = 01100001 n = 01101110

Combined: 010011010110000101101110

Split…