API Security Testing: Importance, Methods, and Top Tools for Testing APIs

APIs play a significant role in seamlessly integrating applications and services. However, APIs with security vulnerabilities could open doors to cyber attackers and compromise sensitive and confidential data and systems. Therefore, it is imperative to incorporate API security testing into the API development process as early as possible.

This article presents an overview of API security testing, its importance, key factors to consider in API security testing tools, and a list of the top API security testing tools available on the market. Additionally, it describes how businesses can improve their API security and mitigate potential cyber threats by leveraging these tools.

What is API security testing?

An Application Programming Interface (API) is the intermediary that enables exchanging data between applications and services to interact with each other. API security testing is the process of evaluating the security of an API. It is mandatory to perform API security testing to reveal any vulnerabilities in an API. Those vulnerabilities can exploit data exchanges between applications and interfere with their normal operations.

API security testing can involve static and dynamic API security tests and software composition analysis (SCA) techniques. 

  • Static API security tests. This type of API security testing helps identify API security issues by examining the source code of an application.
  • Dynamic API security tests. Test the API by sending requests to the application to simulate real-world attacks, including SQL injection attack tests, testing parameter tampering, input fuzzing, using random data in the API, etc.
  • Software Composition Analysis (SCA) tests. SCA is particularly important for using open-source components in APIs. These tests help identify any known vulnerabilities in the libraries or frameworks you use.

(Understand the difference between API testing and API monitoring.)

Why should you test API security?

Currently, many enterprise applications or systems depend heavily on APIs for their functionality, so organizations need to carry out API security testing proactively to identify and mitigate vulnerabilities. The following are the key reasons behind the importance of API security testing:

  • Protecting sensitive data.  APIs often deal with sensitive personal and financial information. The organization will face severe financial losses and reputational damage if such sensitive data is compromised. 
  • Prevent unauthorized access to systems. API security testing helps identify and mitigate vulnerabilities in authentication, authorization, and access control mechanisms, thus preventing unauthorized access to systems.
  • Proactively identify security vulnerabilities. There are common vulnerabilities in APIs like cross-site scripting (XSS), SQL injection, and authentication vulnerabilities. Testing for such issues during the early stages of the development life cycle helps developers fix them before attackers exploit them.
  • Build customer trust and confidence.  Usually, customers expect that their data remains secure when interacting with your business systems. Showcasing your commitment to API security testing fosters trust and confidence among customers.
  • Comply with industry regulations.  There are several cyber security regulations, such as HIPAA and GDPR, that organizations need to comply with when dealing with sensitive data. API security testing helps meet those regulatory obligations.

Features & checklist for API security testing tools

When choosing appropriate API security testing tools for your organization, there are various factors you need to consider. The following are the essential features to seek in API security testing tools to ensure they meet your business requirements.

The API types it supports

Modern enterprise applications consist of different types of APIs. Check the types of APIs you need to support now and those likely to be supported in the future. Does the tool only support HTTP or SOAP requests? Does it support other protocols like GraphQL?

CI/CD support and configurations

Check if the tool allows for the automation of API security testing. Does it integrate well with deployment and testing tools like CI/CD pipelines or test management systems? 

While legacy API testing tools do not support advanced configurations like direct API scanning, modern API testing tools enable direct configuration for API scanning. They use technologies like the OpenAPI Specification or the GraphQL introspection endpoint to obtain comprehensive information about the API. 

Testing capabilities

The testing tool should support various types of API security testing methods, such as injection attacks (SQL injection, XSS), and parameter tampering. Additionally, the tool should facilitate testing for authentication and authorization mechanisms, including security tokens, API keys, etc. 


Performance is another critical aspect you need to consider. The tool should be able to handle large-scale API security testing. Check how much time it would require to build pipelines. Additionally, check if the tool can quickly analyze and validate API requests and responses without introducing high latency. 

(Looking to test for API performance? Read our overview here.)

False positives (FPs) 

A tool with a high false-positive rate would lead to engineering and security teams investing additional effort into unnecessary tasks. Choosing an API security testing tool with minimal false positives is crucial because false positives erode trust in security tools and undermine their effectiveness. 

API security testing tools with a minimal FP rate ensure that security teams can rely on testing results and take appropriate actions based on that information.

Adequate documentation and support 

Proper documentation is crucial for gaining a comprehensive understanding of the tool. Therefore, check if the tool provides adequate documentation, maintenance, and troubleshooting support resources to help users whenever they need assistance.


Carefully reviewing the costs associated with purchasing, using, and maintaining API security testing tools is essential. Additionally, consider whether the tool offers free or open-source options, aligns with your budget, has appropriate cost models and provides features that meet your requirements. It is important to assess these aspects to make an informed decision.

Benefits of using API security testing tools

Organizations can gain numerous benefits by leveraging automated API security testing tools. The following are the key advantages of using API security testing tools.

Reduce the risks of security vulnerabilities

Integrating automated API security testing into your API development tasks lets you detect security vulnerabilities as early as possible. Thus, you can mitigate the risks of introducing security vulnerabilities into your production systems with integrations. 

Improve the productivity of security and development teams 

Automated tools allow the execution of multiple security test cases, which can be a huge time saver when compared to manual execution. Additionally, CI/CD support enables the frequent and automatic execution of security tests as part of the software development process. This allows teams to perform continuous security tests throughout the development lifecycle.

(For more developer productivity success, explore the key components of DPE.)

Improve the overall security posture of the organization

API security testing tools allow organizations to regularly test and address vulnerabilities in integrating systems. Therefore, it helps improve the overall security of your systems and protect against potential cyberattacks.

Top API Security Testing Tools

Currently, many API security testing tools are available on the market. The following list includes the top 10 most widely used API security testing tools. 


A popular tool that allows users to create, test, share, and document APIs. Postman collections enable grouping and sharing of API requests and automated API testing. It supports different authentication methods, including basic authentication, API keys, and OAuth. Other security testing support includes input validation, SSL, and XSS testing.

Apache JMeter

A Java-based open-source API testing tool most widely used for API performance testing — this tool also provides several features for API security testing.


An open-source tool designed to test SOAP and REST APIs and HTTP-based services. Apart from security testing, it supports asynchronous testing, functional testing and performance testing. Its security features allow you to perform security scanning and handle various authentication mechanisms.

Burp Suite 

A testing tool kit primarily used for web application security testing. It also provides features for API testing. For example, Burp Suite's Scanner is useful for scanning and identifying common security vulnerabilities like cross-site scripting (XSS), sensitive data exposure, and injection flaws in APIs.

Apigiee Edge

A powerful tool designed for testing API security, Apigee Edge helps organizations identify and address various security vulnerabilities, including unusual traffic patterns, misconfigurations, and malicious bot attacks within their APIs.


An API testing tool with security features and a web service monitoring tool, Assertible provides automated QA tools and support for continuous integration and delivery. The tool can perform assertions on APIs and validate API security measures. 

Katalon Studio

This software provides a comprehensive solution for API testing, empowering users to create, test, execute test cases, and conduct security testing. Its IDE supports REST, SOAP/1.1, and SOAP/1.2 requests, allowing for versatile testing capabilities.

Sauce Labs

A comprehensive platform designed for testing, monitoring, error reporting, and debugging of web services and REST APIs. It allows users to create dynamic, data-driven, and end-to-end API flow tests and integrates with CI/CD pipelines.


Another open-source API testing tool that can be used for verifying and validating the responses received from API requests. It simplifies the REST API testing process by leveraging Java libraries and seamlessly integrating with Maven. 


A tool that operates on the cloud and provides intelligent automation features — it enables AI & Machine Learning (ML) based testing, integration testing, exploratory, mobile, and regression testing. It also offers a codeless option for non-technical users.

Summarizing API security testing 

API security testing is critical to proactively identifying and addressing security vulnerabilities in APIs. It helps organizations protect sensitive data, prevent unauthorized access, and build customer trust. When choosing a suitable API security testing tool, it is important to consider factors such as API support, CI/CD integration, testing configurations, capabilities, performance, and false positives. With the top API security testing tools described in this article, organizations can leverage automated testing capabilities to reduce security risks, enhance productivity, and improve their overall security posture. 

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This posting does not necessarily represent Splunk's position, strategies or opinion.

Shanika Wickramasinghe is a software engineer by profession and a graduate in Information Technology. Her specialties are Web and Mobile Development. Shanika considers writing the best medium to learn and share her knowledge. She is passionate about everything she does, loves to travel and enjoys nature whenever she takes a break from her busy work schedule. She also writes for her Medium blog sometimes. You can connect with her on LinkedIn.