JWT Security Auditor
Inspect JWT structures, verify claim validity, and check for vulnerabilities offline.
Master This Tool
Deep-dive guides and tutorials for advanced users.
JWT Security Best Practices: How to Decode and Audit Tokens Safely
Learn the JWT security mistakes that actually get exploited — alg:none, algorithm confusion, missing expiry — and how to audit your own tokens safely without sending them to a server.
RS256 vs HS256: Security and Implementation Guide
A deep dive into JWT signing algorithms. Learn why RS256 is the standard for production security and how FmtDev's local-first tools ensure Zero-Server-Logs privacy.
Where to Store JWTs: Cookie vs LocalStorage
Where should you store JWTs? Compare localStorage vs HttpOnly cookies. Learn why localStorage exposes you to XSS and how to secure your 2026 auth flow.
JWT Security: Algorithm Confusion & Secret Exposure
Understand the difference between JWT decoding and verification, and learn how to avoid the dangerous "alg: none" vulnerability.
How to Safely Decode JWTs Without Leaking Secrets
Many online JWT decoders are insecure. Learn why local decoding is the gold standard for developer security.
JWT Security Guides
- Learn more: JWT Security Best Practices
Learn the JWT security mistakes that actually get exploited—alg:none, algorithm confusion, missing expiry—and how to audit your own tokens safely.