API Security: Defending the Layer Attackers Target First

APIs are how modern systems talk to each other, and to customers and partners. That makes them a favourite target: they expose business logic and data directly, and they change often.

The common weaknesses

The OWASP API Security Top 10 is the best starting checklist. Several issues show up again and again:

• Broken object-level authorisation: a user can read someone else's record by changing an ID.
• Broken authentication: weak tokens or sessions that are easy to steal or guess.
• Excessive data exposure: responses return more fields than the client needs.
• No rate limiting: nothing stops abuse or brute-force attempts.

Controls that matter most

• Check authorisation on every request, on the server, for every object
• Validate input against a schema and reject anything unexpected
• Return only the fields each client needs
• Apply rate limits and quotas per client
• Keep an inventory so retired or forgotten endpoints do not linger

Test continuously

Add API security tests to your CI/CD pipeline, run periodic penetration tests, and monitor production traffic for abnormal patterns. Security that is only checked before launch will drift.