dev.to· Oct 28, 2026· by ameenusman

How to decode a JWT in the browser

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A JWT looks secret. It is not. The header and the payload are only Base64url text. Anyone who has the...
🎯 Vulnerability: OAuth 2.0 / JWT Authentication Bypass
💡 Defense Fix: Strictly verify JWT signatures on the backend, enforce state parameter validation, and reject 'alg: none'.
#jwt#webdev#security#javascript