Blog
Practical guides on JWT, authentication, and API security.
The JWT Security Checklist (2026)
Every check that matters before you ship JWT authentication: key strength, algorithm pinning, token lifetime, storage, revocation, and rotation.
How to Store JWTs: localStorage vs httpOnly Cookies
The most-asked JWT question, answered: where tokens should live in the browser, what XSS and CSRF each option really means, and the hybrid pattern most teams ship.
Generate a Secure JWT Secret (2026)
A practical guide to creating cryptographically secure JWT secrets for HS256, HS384, and HS512 — with code examples in Node.js, Python, and the browser.
JWT vs Session Auth: Which to Use?
Stateless JWTs scale beautifully — until you need to revoke a token. Here's a clear-headed comparison of JWT and session-based auth for modern apps.
10 JWT Security Best Practices
From algorithm confusion attacks to leaked secrets, here are the JWT security pitfalls that show up in real production incidents — and how to avoid them.
JWT vs OAuth2: What's the Difference?
JWT is a token format, OAuth2 is an authorization protocol. They're often used together but solve different problems — here's how to think about each.
HS256 vs RS256: Which Should You Use?
HS256 and RS256 solve JWT signing differently — symmetric vs asymmetric keys. Here's how to pick the right one for your architecture and avoid mixing them.
JWT Refresh Tokens Explained
Access tokens should be short-lived, but users don't want to log in every five minutes. Here's how refresh tokens close that gap safely.
JWT Expiration and Clock Skew Explained
The exp and nbf claims look simple until server clocks drift. Here's how to set expiration correctly and tolerate clock skew without weakening security.
JWT Registered Claims Explained
iss, sub, aud, exp, nbf, iat, jti — the seven registered claims from RFC 7519 explained with real examples of how and when to use each one.
The JWT Header Explained
The first segment of a JWT looks tiny, but alg, typ, and kid carry real security weight. Here's exactly what belongs in a JWT header and why.
Storing JWTs: Cookies vs localStorage
Where you store a JWT on the client determines your exposure to XSS and CSRF. Here's an honest comparison of cookies, localStorage, and memory.
JWT Revocation Strategies That Work
JWTs are stateless by design, which makes revocation hard. Here are the denylist, short-expiry, and versioning strategies that actually work in production.
Algorithm Confusion Attacks Explained
One of the most damaging JWT vulnerability classes comes from trusting the alg header. Here's exactly how algorithm confusion attacks work and how to stop them.
JWT Key Rotation with kid and JWKS
Rotating signing keys without breaking active sessions requires the kid header and a JWKS endpoint. Here's how the mechanism works end to end.
401 vs 403 in Token-Based Auth
401 means authenticate, 403 means you're authenticated but not allowed. Getting this distinction right in JWT-based APIs makes debugging far easier.
JWT Auth in Node.js/Express: Step by Step
A complete, practical walkthrough of adding JWT-based authentication to an Express API, from login to protected routes to refresh tokens.