API Security
Pronunciation: A-P-I sih-KYOOR-ih-tee
Definition
API Security is a security mechanism or control discipline that protects application programming interfaces, their data, business logic, credentials, dependencies, and infrastructure from unauthorized use or disruption. API security applies technical and operational controls to interfaces that expose data and business functions.
Overview
Meaning in plain language
API Security is a security mechanism or control discipline that protects application programming interfaces, their data, business logic, credentials, dependencies, and infrastructure from unauthorized use or disruption. API security applies technical and operational controls to interfaces that expose data and business functions.
How it works
API security applies technical and operational controls to interfaces that expose data and business functions. It includes authentication , authorization, input validation, rate limiting, encryption, secure configuration, dependency management, monitoring, and protection of sensitive workflows.
APIs face risks such as object-level authorization failures, broken authentication, injection, excessive data exposure, resource exhaustion, unsafe third-party consumption, and automated abuse of legitimate business functions. An API gateway alone cannot correct insecure application logic.
Teams should maintain an API inventory, define data and trust boundaries, test against misuse cases, protect secrets, and monitor both errors and successful suspicious behavior. Security must cover design, development, deployment, version retirement, and incident response throughout the API lifecycle.
Operators should validate identifiers, timestamps, completeness, provenance, currency or asset units, status semantics, and linkage across requests, deployments, configuration changes, logs, and service responses; missing or delayed evidence should create an explicit uncertainty state.
A production treatment of API Security should test protection of application programming interfaces, their data, business logic, credentials, dependencies, and infrastructure from unauthorized use or disruption within the relevant asset, decision, or service state. The API Security context record for application programming interfaces, their data, and business logic should preserve source data, configuration or policy version, responsible actor, exception, and outcome. Review of API Security should determine whether safeguards addressing application programming interfaces, their data, and business logic changed exposure in practice, not merely whether a document or setting existed.
Where people get it wrong
Encryption alone cannot correct a missing ownership check on an invoice ID. Test abusive but syntactically valid requests as well as obvious malformed input.
Related concepts
Security Incident, API Authorization, Webhook Verification.
Reference
Example
A leaked read-only API token is serious, but a leaked payout-enabled token may permit unauthorized transfers. The API security program must apply authentication, object-level authorization, scoped credentials, input checks, limits and monitoring according to the impact of each operation.
Comparison
API security spans identity, permissions, logic and infrastructure; authentication alone addresses only who is calling.
Key Takeaway
API security must protect business logic and object access, not merely place network controls in front of exposed endpoints.
Sources
- IETF RFC 9110 — IETF (2026-07-30)
- OpenAPI Initiative Documentation: V3.2.0 — OpenAPI Initiative (2026-07-30)
- OWASP Documentation: Www Project Api Security — OWASP (2026-07-30)