Best API Security Testing Tools and Checklist for 2026
Senior Content Marketing Manager
API security testing involves the measures taken to protect APIs from unauthorized access, misuse, and attacks. Because APIs are commonly used and enable access to sensitive software functions and data, they are becoming an increasingly desired target for attackers.
API security is a critical component of modern web application security. API security is essential for protecting sensitive data like financial information or personal data, and preventing attacks that could compromise the integrity of the API and the systems it connects to.
Why is API security testing important?
APIs enable businesses to integrate different systems and technologies by allowing various applications to communicate quickly, leading to more efficient and effective operations.
APIs, however, can also create potential security risks if they are not correctly managed and secured. Attackers have been known to exploit API vulnerabilities to gain access to sensitive data or inject malicious code into applications, leading to data breaches, system crashes, and other serious consequences.
APIs are a frequently targeted attack target. They often handle authentication tokens, personal data, payments, and backend services, making them appealing to attackers. Attackers favor APIs because they are predictable, highly automated, and often less protected than user-facing applications.
What to look for in an API security testing solution
Strong API security testing should be applied throughout the API lifecycle, considering all potential areas for exploit and looking at the entire ecosystem as a whole. You can read this complete API security testing best practices for more.
API security testing checklist
Ensure you are addressing security in the following areas for a robust API security strategy.
Authentication and access
Use strong authentication (OAuth 2.0 / API keys)
Enforce least-privilege scopes
Rotate and revoke keys regularly
Transport and data
Require HTTPS everywhere
Encrypt sensitive data at rest and in transit
Never log secrets or tokens
Input and output
Validate and sanitize all inputs
Enforce strict schemas (reject unexpected fields)
Prevent over-exposure in responses
Rate and abuse protection
Apply rate limiting and quotas
Protect against brute force and replay attacks
Monitor for abnormal traffic patterns
Errors and visibility
Return generic error messages
Log security events centrally
Enable alerting for auth failures and spikes
Maintenance
Keep dependencies up to date
Run regular security testing (linting, SAST, fuzzing)
Document and review API changes
What types of API security testing tools exist?
Organizations typically use a mix of:
API scanners and fuzzers
Dynamic and interactive testing tools
Penetration testing platforms
Runtime protection and monitoring solutions
WAF, bot management, and edge security tools (like a CDN)
No single tool covers every risk. A layered approach to layered testing is key.
What API security testing activities should you perform?
API discovery and inventory scanning tools. These tools find unknown, shadow, and zombie APIs
Schema and specification validation tools. These tools detect schema drift, contract violations, and over-exposure.
Dynamic API vulnerability scanning, using DAST solutions. These tools test live APIs for common vulnerabilities.
Business logic and abuse scanning. These solutions detect authentication bypass, object-level authorization flaws, and logic abuse.
Authentication and authorization testing. These solutions validate OAuth, JWTs, scopes, and access controls.
Fuzzing and negative testing. These tools send purposefully malformed, unexpected, or edge-case inputs to see how the system will react.
Runtime behavioral analysis. These tools detect anomalies, bots, and active attacks.
CI/CD and shift-left API Scanning. These solutions scan specs and APIs before production.
Dependency and supply chain scanning. These solutions aim to find vulnerable SDKs and API dependencies.
Rate-limiting and resilience testing. These tools test throttling, quotas, and abuse resistance in the system.
The best API security testing solutions
Fastly
Fastly delivers a comprehensive runtime API security solution built into its edge cloud platform, giving teams real-time visibility and protective control over API traffic as it flows through a globally distributed network.
Its API Discovery automatically maps and inventories APIs identified at the edge, helping you uncover unknown or shadow APIs and understand how they’re used. Fastly’s Next-Gen WAF provides advanced Layer 7 protection against the OWASP API Top 10 risks and more, inspecting API traffic including REST, GraphQL, gRPC, and WebSockets for malicious or anomalous behavior.
Leveraging contextual detection with SmartParse and collective threat intelligence from the Network Learning Exchange, Fastly blocks abusive traffic, bot activity, credential abuse, and other threats with minimal tuning required.
Additional protections include edge-enforced rate limiting, bot management, and DDoS defense, all with detailed telemetry and flexible deployment options that align with DevOps workflows and CI/CD toolchains. The result is scalable, edge-native API security that improves resilience, reduces manual effort, and unifies visibility and enforcement across distributed environments.
Cloudflare
Cloudflare provides a comprehensive, edge-native API security solution designed to protect modern API-driven applications against a wide range of threats ranging from volumetric abuse and zero-day exploits to data leakage and business logic attacks. Its API Shield offering brings together automated API discovery, schema validation, and positive security models to catalog and protect both known and shadow APIs, ensuring only traffic that matches expected schemas and authentication policies is allowed through. Cloudflare’s platform supports strong authentication mechanisms including mutual TLS (mTLS), JWT, OAuth tokens, and API key validation at the edge, effectively blocking illegitimate clients before they reach origin systems.
Imperva
Imperva delivers a unified, enterprise-grade API security solution that helps organizations gain full visibility and control over their entire API landscape, including public, private, and shadow APIs. Imperva continuously discovers and classifies all API endpoints, ensuring that hidden or forgotten APIs are identified and assessed for risk. Its platform combines real-time detection with behavioral and rule-based analysis to identify attacks like Broken Object Level Authorization (BOLA), business logic abuse, and other threats from the OWASP API Security Top 10.
Akamai
Akamai provides a robust, enterprise-grade API security solution that helps organizations protect their entire API estate with comprehensive visibility, behavior analysis, and threat mitigation capabilities. Its API security platform continuously discovers and inventories APIs including shadow, legacy, and modern GenAI/LLM-linked endpoints, giving teams full visibility into their attack surface. By analyzing API activity with behavioral analytics and automated detections, Akamai surfaces anomalies, abuse, and patterns associated with sophisticated attacks, and ties those insights back into real-time defenses.
How Fastly can help
API security testing should be an ongoing effort. By combining secure design, continuous automated testing, manual validation, bot-aware abuse testing, and edge-based protection, organizations can significantly reduce the risk of API exploitation while maintaining performance and scalability.
Fastly API Security gives you the full picture of your API landscape. You can understand what exists, gain confidence that things are working as expected, and make targeted API abuse mitigation decisions across the Fastly platform.
Fastly’s Edge Cloud Platform inspects and filters API requests at its globally distributed edge locations. This means malicious or abusive traffic like bot-driven attacks, credential stuffing, or API scraping can be blocked or throttled before it ever reaches your application servers. Stopping threats early reduces backend load, lowers latency, and limits blast radius during attacks.