What is API Security? Definition & Explanation
API Security is the practice of protecting application programming interfaces (APIs) from misuse, abuse, and attacks throughout their lifecycle. It includes authentication, authorization, rate limiting, schema validation, and continuous monitoring to defend against the OWASP API Security Top 10 risks.
In-Depth Explanation
Modern applications expose hundreds of internal and external APIs (REST, GraphQL, gRPC, SOAP), each a potential attack surface. API Security covers design-time threat modeling, build-time schema validation, runtime authentication (OAuth 2.0, API keys, mTLS), authorization (RBAC, ABAC, scopes), rate limiting, input validation, output encoding, and runtime protection via Web Application and API Protection (WAAP) platforms. The OWASP API Security Top 10 (2023 edition) highlights Broken Object Level Authorization (BOLA), Broken Authentication, Excessive Data Exposure, and Server-Side Request Forgery (SSRF) as the most common API risks. Mature API security programs maintain a discoverable API inventory, automate schema-based fuzzing in CI, monitor production traffic for anomalies, and integrate with API gateways like Kong, Apigee, AWS API Gateway, and Azure APIM for centralized policy enforcement.
Why It Matters for Security
APIs now drive over 80% of internet traffic and are responsible for some of the largest breaches in recent memory — Optus (2022), T-Mobile (2023), and Twitter all suffered API abuse incidents exposing tens of millions of records. Unlike web apps, APIs lack a UI to inspect, making misconfigurations and authorization bugs invisible until exploited. API security is now a top priority for AppSec teams and a required control for SOC 2, PCI DSS, and ISO 27001 compliance.
Related Tools
- Checkmarx One Platform
Unified AppSec with AI-powered SAST, SCA, DAST, API security and supply chain protection.
- Apiiro Platform
AI-powered application risk management with code behavior analysis and risk graph visualization.
- Apiiro Risk Graph
Code risk platform mapping application architecture to prioritize security issues by business impact
Frequently Asked Questions
What does API Security mean in cybersecurity?
API security in cybersecurity refers to the policies, tools, and practices that protect application programming interfaces from unauthorized access, data exposure, abuse, and attacks like Broken Object Level Authorization (BOLA), credential stuffing, and SSRF — across design, build, and runtime stages.
Why is API Security important?
API security matters because APIs are now the dominant attack surface in modern applications, driving over 80% of internet traffic. Unlike traditional web vulnerabilities, API flaws are often invisible to standard scanners and have caused several of the largest data breaches of the last decade.