What is Base64?
Base64 writes binary data using only 64 safe characters (A–Z, a–z, 0–9, + and /), so it can travel through email, JSON, URLs and HTML. Every 3 bytes become 4 characters, so the encoded data is about 33% larger.
- URL-safe Base64 uses - and _ instead of + and /, and drops the = padding. It is used in JWT tokens and URLs.
- Data URIs such as
data:image/png;base64,iVBOR…embed small images directly in HTML or CSS. - Base64 is encoding, not encryption: anyone can decode it.
Frequently asked questions
How do I decode a JWT token?
A JWT has three parts separated by dots. Paste the middle part (the payload) in Decode mode. It is URL-safe Base64, which this tool detects automatically.
Is my file uploaded?
No. Files are read and encoded in your browser and never leave your device.