What Is a JWT Token?
JSON Web Tokens (JWTs) are a compact way to represent claims between two parties. They're widely used for authentication in modern web apps.
JWT Structure
A JWT has three parts separated by dots:
1. Header — Algorithm and token type
2. Payload — Claims (user ID, roles, expiry)
3. Signature — Verification hash
Why Decode JWTs Client-Side?
JWTs contain sensitive claims like user IDs, email addresses, and permissions. Pasting them into online tools that send data to servers is a security risk. Always decode JWTs in your browser.