What is API Security?
API Security is the practice of protecting application programming interfaces from unauthorized access, abuse, and data exposure. It covers discovery, authentication enforcement, traffic inspection, and runtime protection for REST APIs, GraphQL endpoints, and other web services.
What it does
API security tools protect the interfaces that applications use to communicate. They typically:
- Discover APIs automatically, including shadow and undocumented endpoints
- Enforce authentication and authorization policies, such as OAuth scopes and least-privilege access
- Inspect request and response payloads for malicious input or sensitive data leakage
- Block traffic that matches known attack patterns, including the OWASP API Security Top 10
- Track schema drift, flagging when an API changes in ways that introduce risk
- Log API calls for audit and forensic purposes
Some tools run as gateways or proxies. Others embed controls directly in application code or operate agentlessly by analyzing cloud configurations.
Why teams buy it
APIs are now the primary attack surface for web applications. A single misconfigured endpoint can expose a full database. Common failures include broken object-level authorization, excessive data exposure, and missing rate limits. These are distinct from the vulnerabilities that a Web Application Firewall alone is designed to catch.
Teams also buy API security tools to gain visibility. Many organizations do not have an accurate inventory of their own APIs. Discovery features surface endpoints that developers deployed but never registered with a security team.
What to look for
- Discovery scope: Can the tool find APIs across cloud accounts, microservices, and third-party integrations without requiring manual registration?
- Schema validation: Does it compare live traffic against an OpenAPI or GraphQL schema and alert on deviations?
- Authentication controls: Does it enforce token validation, certificate pinning, or claims-based access at the gateway or runtime layer?