What is a JSON Web Token?

Compact, signed token for secure data transmission—header.payload.signature, readable payload, tamper-proof sig.

How do you decode a JWT without a library?

Split by dots, atob() the payload chunk (fix +/=, parse JSON. Browser console does it.

No—payload's public. Stick to IDs, roles. Secrets server-side only.

Paste a JWT into your browser console, and boom—user IDs, emails exposed. Signed, not encrypted: that's the genius and the trap of JSON Web Tokens.

theAIcatchup Apr 10, 2026 3 min read

JWTs are signed, not encrypted—payload readable, signature prevents tampering. 𝕏
Common pitfalls: no sig verification, weak algs, sensitive data leaks. 𝕏
Scale with short expiries, RS256, and revocation via jti for production safety. 𝕏

Published by

Community-driven. Code-first.

#API security #JSON Web Token #JWT #authentication #web security

Get the best Open Source stories of the week in your inbox — no noise, no spam.

Originally reported by Dev.to