How to secure cloud APIs with OAuth2 and OpenID Connect

· Category: Cloud Computing

Short answer

OAuth2 delegates authorization; OpenID Connect adds an identity layer on top for authentication.

Steps

  1. Choose an identity provider (Auth0, AWS Cognito, Azure AD, Google Identity).
  2. Register your API and define scopes.
  3. Implement the appropriate OAuth2 flow (client credentials, authorization code, PKCE).
  4. Validate JWT access tokens in your API.
  5. Use refresh tokens for long-lived sessions securely.

Tips

  • Prefer authorization code with PKCE for mobile and SPAs.
  • Keep tokens short-lived and rotate refresh tokens.
  • Use scopes and claims for fine-grained access control.

Common issues

  • Leaking client secrets in public clients; use PKCE instead.
  • Token size limits with large claim sets.