Building Secure APIs and Services

APIs connect apps and services. A secure API reduces risk, protects user data, and builds trust across teams and customers. Good security should be baked in from the start, not added after a breach.

Begin with threat modeling. Map data flows, identify who uses the API, and where data travels. List threats like broken access control, injection, and misconfiguration. The goal is clear protection and measurable risk.

Authenticate users and machines with proven standards. Prefer OAuth 2.0 and OpenID Connect to issue tokens. Use short-lived access tokens and rotate them. Store refresh tokens securely and never in client code. Validate every token on each request: audience, issuer, and expiration. Enforce scopes and roles to limit access.

Protect data in transit with TLS 1.2+ and strong ciphers. Use HTTPS everywhere. Validate inputs with allow-lists for names, IDs, and sizes. Sanitize outputs to avoid leaking internal details. Encrypt sensitive data at rest and manage keys with a trusted service.

Design for resilience. Use an API gateway or service mesh to handle authentication, rate limiting, and IP filtering. Apply quotas, backoff, and sensible error messages that don’t reveal sensitive details.

Logging and monitoring. Record who accessed what, when, and from where. Watch for unusual request patterns, failed tokens, and spikes in errors. Set alerts and have an action plan for incidents.

Secure development lifecycle. Automate security checks in CI/CD, scan dependencies, and test for common flaws. Review code for secrets exposure and perform regular pen tests. Keep libraries and frameworks up to date.

A practical starter checklist helps teams move fast.

  • Enforce TLS 1.2+ for all endpoints
  • Adopt OAuth2 / OpenID Connect and short token lifetimes
  • Validate inputs and enforce strict data handling
  • Apply rate limiting and sane quotas
  • Centralize logging and set alerts
  • Keep dependencies up to date

Key Takeaways

  • Default to secure by design: TLS, tokens, input validation.
  • Use OAuth 2.0 and OpenID Connect for authentication and authorization.
  • Monitor, log, and test continuously to detect and respond to threats.