What Is Base64?

Base64 is a way to represent binary data (images, files) as plain text. Why would you need that? Because formats like JSON, XML, and email only support text — you can't shove raw PNG bytes into a JSON body. Base64 uses the characters A-Z, a-z, 0-9, +, and / to encode binary data into a safe text string that can go anywhere text goes.

When You'll Need It

API image uploads — skip multipart forms by Base64-encoding the image into the JSON body
Email attachments — MIME uses Base64 to encode file attachments
Data URIs — embed small images directly in CSS or HTML to save an HTTP request
JWT tokens — the header and payload sections of a JWT are Base64url-encoded

Things to Know

Topic	Detail
Size increase	Base64 output is roughly 33% larger than the original data
Not encryption	Base64 is encoding, not encryption. Anyone can decode it — never use it to protect sensitive data
Unicode support	Non-ASCII characters (CJK, emoji) need to be converted to UTF-8 bytes first — this tool handles that automatically