// ROUTE_TRANSITION_SYS :: BLOG/OAUTH2 JWT AUTH SECURITY BEST PRACTICES/
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// KROMA CODE BLOG :: BACKEND ARCHITECTURE
Modern Authentication Architecture: OAuth2, PKCE, Refresh Token Rotation, and Passkeys
Shishir Singh• 12 min read•July 23, 2026
💡 ARTICLE EXECUTIVE SUMMARY: "Storing JWTs in localStorage exposes user sessions to XSS attacks. Learn how to architect bulletproof auth systems with HTTP-only cookies, PKCE flow, and WebAuthn Passkeys."
1. The Vulnerability of LocalStorage Session Storage
Many frontend developers store JSON Web Tokens (JWT) inside browser localStorage. If a application suffers a cross-site scripting (XSS) vulnerability via a third-party npm package, malicious scripts can steal user JWTs directly and hijack user accounts permanently.
2. Production Auth Architecture Standards
- SameSite HTTP-Only Cookies: Store short-lived access tokens (15-min expiry) inside secure, SameSite=Strict, HTTP-only cookies unaccessible to JavaScript DOM.
- Refresh Token Rotation: Issue single-use refresh tokens stored in Redis. If a refresh token is reused, revoke the entire token family immediately.
- OAuth2 with PKCE: Enforce Proof Key for Code Exchange (PKCE) for mobile and single-page application auth flows.
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Backend APIs & Database Architecture // FEATURED CASE STUDY
SGMS World Enterprise System Written by Shishir Singh (Founding Engineer at Kroma Code, Lucknow)
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