Table of Contents
Quick Answer
Use AI to scaffold OAuth2/OIDC flows — but never trust it to design your auth. Follow Authlib, Auth.js, or Passport patterns, enable PKCE for public clients, and validate state and nonce on every callback.
- AI accelerates OAuth boilerplate but security review must be human
- Use a battle-tested library (Auth.js, Clerk, Supabase Auth) instead of rolling your own
- Always use Authorization Code + PKCE; implicit flow is deprecated
What You'll Need
- Target provider (Google, GitHub, custom OIDC)
- Next.js, Node, Python, or Go backend
- HTTPS (mandatory — no exceptions)
- Secrets storage
Steps
- Register the OAuth app. Provider console: set redirect URI exactly matching prod and dev.
- Pick a library. Next.js: Auth.js. Python: Authlib. Go: golang.org/x/oauth2.
- Configure the provider. Prompt:
Write Auth.js config for Google OIDC with offline access and PKCE. - Initiate login. Redirect user to authorization endpoint with state and code_challenge.
- Handle callback. Verify state, exchange code + code_verifier for tokens at token endpoint.
- Validate ID token. Check
iss,aud,exp, and signature against JWKS. - Store tokens. Access token: short-lived session cookie (httpOnly, Secure, SameSite=Lax). Refresh token: encrypted at rest.
- Refresh flow. Before expiry, use refresh_token at token endpoint. Rotate refresh tokens if provider supports.
Common Mistakes
- Skipping state verification. Enables CSRF.
- Storing tokens in localStorage. XSS steals them instantly. Use httpOnly cookies.
- No PKCE for public clients. SPAs and mobile apps must use PKCE.
- Trusting email as identity. Different providers allow email changes — use
subclaim as identifier.
Top Tools
| Tool | Purpose |
|---|---|
| Auth.js (NextAuth) | Next.js OAuth |
| Clerk | Managed auth |
| Supabase Auth | Self-hosted OAuth + DB |
| Keycloak | Self-hosted OIDC IdP |
| jose | JWT validation |
Conclusion
OAuth2/OIDC is unforgiving of shortcuts. Let AI scaffold from a battle-tested library; let humans review. For Misar's cross-TLD SSO pattern see id.misar.io. Build your next app on Misar Dev with OAuth wired in one click.