Avoid building bespoke authentication protocols. Leverage industry-standard frameworks like OAuth 2.0 for authorization and OpenID Connect (OIDC) for authentication. This addresses OWASP API2:2023 Broken Authentication.

• Use the Authorization Code Flow with PKCE for mobile and single-page apps.
• Do not use the deprecated Implicit Flow.
• Delegate identity management to specialized providers (e.g., Okta, Auth0, AWS Cognito).

import { auth } from 'express-oauth2-jwt-bearer';

const checkJwt = auth({
  audience: 'https://api.mycompany.com',
  issuerBaseURL: 'https://mycompany.auth0.com/',
});

// Apply to all API routes
app.use('/api', checkJwt);

app.get('/api/secure-data', (req, res) => {
  res.json({ data: "This is secured by OAuth 2.0!" });
});