API Testing Checklist: 10 Steps to Start API Testing

Timothy Joseph
Timothy Joseph | September 29, 2020

API Testing Checklist: 10 Steps to Start API Testing

APIs bridge the communication gap between an application and third-party apps. If an API doesn’t work efficiently or effectively, it can negatively impact software quality and business processes.

It’s hard to argue against the need to test APIs. However, how to do API testing can quickly become a confusing process.

That’s where an API checklist comes into play. After all, it’s easier to test APIs when there are defined steps to complete during the API testing phase. Creating an API security testing checklist can result in having more questions. For example, what is API testing? Why is API testing important? And what’s the best method when testing APIs?

Consider this API security checklist as your comprehensive web API testing tutorial on how to do API testing, from evaluating key considerations for API testing to exploring these 10 steps to start API testing.

What Is API Testing?

API testing verifies the health of Application Programming Interfaces (APIs). With a strong API checklist, QA teams review the security, functionality, reliability and performance of all APIs within the software application.

By following the steps outlined QA engineers can thoroughly examine the business logic layer of the software’s architecture instead of the design and experience of the user interface.

Why a Checklist for API Testing is Important

With the right API checklist and QA team project management process in place (FREE worksheet here), your team can expect to see an array of benefits that positively impact your development cycles and the quality of your software product.

An API audit checklist is important because:

  • It improves test coverage - Because API specifications allow for easy automation, testers can detect errors sooner before they grow into bigger problems.
  • It’s more cost-effective - Since API automated testing requires less coding, QA testing becomes a faster, more affordable process.
  • It provides stronger security - APIs are designed to remove common vulnerabilities within a software product, so following an API security checklist means more protection for your application.
  • It’s language-independent - By exchanging data via JSON or XM, QA testers can select any core language when API testing.
  • It integrates simply with GUI - An API security testing checklist means executing highly integrable tests when performing functional GUI testing.

Types of Tests to Perform on Your APIs

We recommend that you include these types of API tests within your API checklist:

  • Validation Testing

    This high-level focus of the testing process occurs at the end of the development cycle to validate that the API’s basic parts and functions are complete. Validation testing follows its own API audit checklist when examining the behavior and efficiency of the APIs within the software product.

    Successful validation testing should answer the following questions to confirm a thorough examination has taken place.

    • Does the API resolve the addressed issue?
    • Does any unrelated code within the software product impact the behavior of the API?
    • Does the API access the correct data through an established behavior path?
    • Does the API access any unnecessary data, especially data that could jeopardize any confidentiality and integrity requirements?
    • Does the API complete the request accurately?
    • Does the API apply the most efficient method when completing the request?
  • UI Testing

    This type of API testing examines the user interface. UI testing focuses on the interface experience that ties into the API to verify that the user experience is as expected. By creating an API testing checklist, QA teams examine the health, efficiency and usability of both the front-end and back-end of the software application.

  • Security Testing

    Security tests aim to uncover any vulnerability, threat or risk within the API so that malicious attacks from both internal users and intruding criminals can be prevented. With a solid API security testing checklist in place, security testing can identify all possible loopholes and API weaknesses that can potentially result in a loss of information, revenue and reputation. An API security checklist should include penetration testing and fuzz testing in order to validate encryption methodologies and authorization checks for resource access.

  • Load Testing

    Load tests review the API’s performance under specific load, by simulating spikes in user activity. QA testers should examine how well the API behaves with a spike in users accessing the system. After following an API testing checklist, QA teams can confirm the expected load of an API with exact data and accurate numbers.

API Testing Checklist

We consulted with our expert API engineers at QASource to provide you a comprehensive and up to date checklist API testing checklist. This API checklist can guide you on how to execute all types of API testing so that you can produce accurate and reliable results.

Here are some of our 10 steps to start API testing so that you know what needs to be completed and what questions to ask throughout the API testing process:

  • Evaluate Your Team's Knowledge

    Do your team members understand API architecture? Do they have an understanding of API testing tools and automation tools? Do they have programming skills?

    If your team is not proficient in these areas, consider adding to your API checklist a process for evaluating the knowledge set of your QA teams. By reviewing their current understanding of APIs, you can understand which aspects of testing APIs need further review and regular training.

  • Set Up Your Environment

    Has your database and server been configured to set up the test environment needed for testing APIs? Has the test data been defined according to output and input parameters? Do you have enough QA testers, either internal employees or outsourced resources, assigned to all API test cases?

  • Define Your Test Plan

    This is an important step in creating your API testing checklist because a well-defined test plan can help prevent delays. Does your plan define the priority of API scenarios? Are all positive and negative test scenarios included? Does the plan explain data sets to be used during testing?

  • Select Your Tool for Manual API Testing

    Choose an API testing tool that can support your API architecture, is easy to learn with intuitive features, and allows you to manage execution, including report compiling. Your API checklist should include steps that guide you through the selection process of a manual API testing tool as well as onboarding testers and implementing the tool within your testing procedures.

  • Define Execution and Defect Reporting

    Have you defined strategies and processes for the periodic execution of tests, monitoring and defect reporting? Does your strategy analyze and report test failures as defects in the defect tracking system?

Next Steps for Your API Security Testing Checklist

APIs are a critical piece of an application as our society becomes more and more interconnected. These steps mentioned above and the steps in our checklist 10 Steps to Start API Testing are designed to help an engineer, testing provider and/or a software company start the process of testing APIs. Check out our API testing checklist below to learn 10 steps you must follow when API testing.

Does your team need more assistance to move this process forward? Consider partnering with a professional QA services provider like QASource. Our team of security testing experts are highly skilled in API testing and can help you create a strong API checklist for testing your software application. Get in touch with a QASource expert today.

Download your free checklist below and discover the steps that need to be completed before testing APIs.


This publication is for informational purposes only, and nothing contained in it should be considered legal advice. We expressly disclaim any warranty or responsibility for damages arising out of this information and encourage you to consult with legal counsel regarding your specific needs. We do not undertake any duty to update previously posted materials.