API Testing Pillars

As APIs have led the way to IT modernization and are the new fabric of IT infrastructure, active and aggressive API testing has become crucial. Comprehensive Functional, Performance, Interoperability and Vulnerability Testing form the Pillars of API Testing. Only by adopting a comprehensive testing stance, enterprises can ensure that their API strategy is robust, scalable, interoperable, and secure.
APIs have blurred the boundaries between network devices, security products, applications and other IT assets within an enterprise. Almost every IT asset now advertises its interface as an API interface ready for XML/JSON messaging.  API interfaces provide unprecedented flexibility in integrating IT assets across internal and external corporate domains. Such flexibility makes it the responsibility of IT staff from all domains such as Developers, Network Engineers, Security & Compliance Officers, and Application QA Testers to ensure that their APIs work as advertised across functional, performance, interoperable and security requirements.

Pillar I: Functional &Regression Testing

Functional and Regression Testing is the First pillar of testing APIs. IT Professionals need to quickly test APIs and setup desired regression Test Cases. Ease-of-use in setting up such tests encourages technologist with varying skills and responsibilities to test their APIs quickly and often. Simple Test Case Management and Setup is paramount to lowering the time required for setting up and maintaining functional & regression tests.

Pillar II: Performance

Performance is the Second Pillar of API Testing. QA Testers, Network & Security Engineers should test the scalability and robustness of Web Services and determine performance and endurance characteristics of their API interfaces. Testers should determine response times, latency, throughput profiles for target Web Services. In addition to performance profiles, tester should run test for a specified duration for measuring endurance and robustness profiles. They also need to determine scalability by bombarding target APIs with varying messages across a range of concurrent loading clients.

Pillar III: Interoperability

While loading an API, consumer applications need to determine both design-time and run-time interoperability characteristics of the target API behavior. Developers should run a set of comprehensive  tests and report interoperability issues.  Design-time interoperability testing is not enough.  Run-time interoperability testing is also necessary. Testing the interoperability of an API requires creating specialized test suites.  These tests ensure that the target API is interoperable by actively sending specialized requests to the API and determining whether the API responds per expected specification. Comprehensive design-time API profile assessment combined with active run-time API interoperability behavior testing ensures that IT assets can integrate independent of platform, operating system, and programming language.

Pillar IV: Vulnerability Assessment

Vulnerability Assessment is the Fourth Pillar of API Testing. Active API Vulnerability Assessment is a necessary area of API testing in the current landscape of API threats. By creating specialized tests for an API, security officers can measure the vulnerability profiles of the target API.  Security Engineers need to ensure that API vulnerabilities such as buffer overflows, deeply nested nodes, recursive payloads, schema poisoning and malware traveling over API messages do not affect their critical API-based applications. They need the ability to rapidly scan APIs and assess areas of exposure, determine severity levels, provide vulnerability diagnosis, and publish remediation techniques. API Vulnerability Assessment is a crucial pre-production and post-production step that every API developer and security professional must take to ensure risk mitigation within their API Architecture.


APIs are the foundations of modern distributed systems. The widespread use of APIs across mobile, cloud, and B2B applications mandates that all IT professionals take responsibility of testing their APIs before and after publishing them to consumers. Developers, QA Tester, Network & Security Engineers should be responsible and accountable for ensuring that their APIs are robust, interoperable, scalable, and secure. Crosscheck Networks’ SOAPSonar™ – an industry-first product that addresses all Pillars of API testing – enables IT professional with varying API testing capabilities to quickly take control of deploying comprehensively tested and high quality APIs.

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