Written By :Appsierra

Sat Dec 16 2023

5 min read

What is API Integration testing and Validation

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API Integration testing

API integration testing has become a fundamental step in the software industry. It efficiently monitors the performance, reliability, and security of different interconnected software APIs in an application. Furthermore, elevates your software output to another level. To know more, let us scroll down and grab more insights in this blog!

Multi-functional apps are today's reality - Thanks to the key concept that smoothly coordinates different services in a single software application. One such example is eCommerce apps, food delivery apps, and ride-hailing services; all have built-in Google GPS service. Consequently, this trend-setting idea is producing a lot of capital profit for businesses. Thus, all the real credits go to API integration testing.

But what precisely are the APIs? They are the backbone of today’s digital globe. Opting for integration testing services helps developers obtain a clear action plan. Hence, it is the APIs that lead them to employ best practices with advanced technology. Ultimately, it boosts the product quality and establishes a good user experience.

But how? To have clear insights, read our guide on API integration testing below!

What does API integration testing mean?

Let’s break it down to simple terms, Application Programming Interface or API is a set of rules, protocols, and tools. As a result, we can define it as a process of connecting multiple software systems through their APIs to enable them to work together cordially. API sets boundaries to allow only a certain level of communication between applications as per criteria.

What do the statistics say?

The global API testing software market was estimated to be worth $441.3 million in 2020 and is expected to grow to $1,199.4 million by 2025 while foreseeing an overall CAGR of 20.5%.

So, by now, you might have understood the concept of API integration testing. Let us go through its benefits in the next section.

What are the benefits of API integration testing?

API integration testing works with limits better than any other method. From exposing a free API to product release, it understands client requests and works indifferently to meet them. As a result, below are more such benefits that make it a standard and special technique:

Quick bug fixes

API integration testing works to show results rapidly. As a consequence, positive or negative testers can see the results straight away. Moreover, this helps troubleshoot at early stages like system development, ensuring bug discovery and elimination.

Low testing costs

The early implementation of automation API testing helps in effective resource usage. At the same time, overall testing expenses become cheaper. As a result, even before UI testing, we can identify any problems & reduce the price of future application updates.

Allow all programming languages

API testing can be done with any language because data is sent using XML and JSON standards. Therefore, you can work with either Java, JavaScript, or Python. API integration testing also helps in the quicker release of products, saving a lot of time.

UI tests can be integrated

Fully integrated tests can be done with API testing. Consequently, if you presume to do UI testing after API, it will turn out to be a good advantage. For simple integration before performing UI testing, it's also possible to add new users to the application.

Want to know the popular tools used for API integration testing? In the next section, we will give you insights that help you choose the right tools.

What are the popular API integration testing tools?

Software developers can design APIs using a variety of architectures, but REST and SOAP are the most prevalent. As per product needs, we can reuse those code scripts or create new services easily with testing tools for API integration. So, we have listed below the top testing tools:


Katalon is suitable for both mobile apps and APIs. As a result, it offers excellent customization commands in addition to CI/CD integrations. Moreover, it's easy for non-techies to use. Its free plan supports equal tester success in automation and exploratory testing.


With the Postman API tool, it's easy to supervise the APIs and build required automated tests. Additionally, it also makes it easy to carry out the debugging and send out requests. Also, Postman extends its features to Windows and macOS and is a free tool that uses highly innovative techniques.


SoapUI allows both SOAP APIs and RESTful web services for testing. In all honesty, most testers prefer this tool for its data-driven testing and user-friendliness. As a result, its free option is simple to use, while the paid one supports CI/CD integrations and custom code creation.


Apigee is a JavaScript-based, intriguing cross-cloud testing tool. As a result, with this tool, the API integration testing is done with a lot of data and response rates. It also offers a free trial to quickly resolve any performance problems and helps you choose the best package to utilize.

So, these are a few of the API integration testing tools. But remember, there is a long list to go through. Therefore, scroll down for more insights on the steps involved in performing API testing. 

How to perform API integration testing?

In a recent survey, 43% of respondents said APIs generate a quarter of company revenue. So, attaining seamless interconnection within systems can be possible for any business sector. As a result, it only requires performing integration API testing in a standard approach. The steps are as follows:

Setup the test environment

First, identify the APIs that need integration into the application. Next, create a production environment and a separate testing environment for integration. Install necessary tools like Postman, Swagger, etc., and frameworks. In the end, configure the test environment with relevant data.

Planning and strategy

Define the testing efforts and scope of your APIs with integration points. Then, make a list of test scenarios to cover all integration points. Determine the correct order of APIs to simulate real-time usage. In addition, set specific criteria for test scenarios to give a “pass” and “fail.” Lastly, record the plan, objectives, testing approach, and test strategy to ensure successful outcomes.

API test design

To begin, select one of the White-box, black-box, or gray–box testing techniques to use. As a result, to harmonize the levels of API access, develop elaborate test cases for every possible API endpoint, input, and response. Finally, keep all this data noted together with the description of test cases, as it will help maintain tests.

Test data preparation and execution

Test data collecting should comprise valid and invalid datasets. Eventually, incorporate some test cases for the complete test. Create data fixtures to ensure that there are uniform sources of data. Lastly, execute them in predefined order using automated testing tools or manual tools. Also, run tests, follow their progress, and record log errors.

Error handling and negative testing

Check for correct HTTP status codes and verify how API handles errors and exceptions so that API can smoothly handle invalid and unexpected input without system failure. Additionally, evaluate the system’s resilience by intentional errors and verify its recovery status. It's necessary to do performance testing and security testing in order to improve quality.

Test integration, reporting, and maintenance

First, verify compatibility with external systems. Then, integrate necessary APIs with consistent data. Record all the test results pass/fail statuses in a detailed log. Also, generate test reports and summarize results to release products. Further, for test maintenance, constantly update test cases, re-run integration tests, and review test coverage results for the long run.

It's a lengthy process but yet productive! So, moving to the next section, we will give you clear pointers to follow about choosing API integration testing tools.

How to choose the right API integration testing services?

The nature of the API testing process demands that it operates using efficient testing tools. As a result, it’s often confusing to choose the right tool amongst numerous options. So, let’s explore these tips that often help developers choose the right testing service for their workplace:

Based on the complexity

Some testing tools need coding knowledge, while others can be more user-friendly for non-tech people. Based on the team's skill set and the complexity of the software to be designed. It’s also advantageous to choose a tool that satisfies both of them.

Budget-friendly option

The costs of using such tools vary depending on the software we work with and the features we need. So, it is better to review the list of tools that meet the criteria first and then choose the testing software that aligns best with the budget.

Accurate API documentation

It’s challenging to maintain API documentation manually. So, better look for software that generates API documentation. As the application progresses, make sure that test results are organized as per client requests with collections for reuse.

Consider team size

Including developers and testers, the testing team can be quite large. In that case, opt for software that includes a synchronization option across the team. Tools that allow sharing function as a feature make teamwork much more efficient.

Want to know the real-life API integration testing examples? The next section will be perfect know-how to understand the real purpose of this testing.

API integration testing: examples to look for!

In real-life scenarios, many software developers and testers use integration testing services. Considering their ability to elevate application performance while fixing error rates efficiently. So, let’s explore some of such examples:


Founded in - 2010

Location - USA

When you open the UBER app, it allows users to log in with their Facebook or Google account. Notably, Google and Facebook are exposing a level of user information based on their agreement. In this UBER login, APIs are interconnected and work with Google and Facebook membership APIs. This is possible owing to successful API integration testing.


Founded in - 2004

Location - USA

Kayak is one of the biggest online sites for ticket booking. First, you enter the destination and select dates. By clicking on search, you get results from all possible airlines matching your schedule. Here, all airlines are exposing their information as APIs, which are aligned with Kayak search engine APIs. The app serves a smooth booking process, all thanks to API integration testing. 


API integration testing focuses on APIs directly to verify whether they meet expectations regarding functionality, performance, reliability, and security. This is a cost-effective yet important add-on in software development architecture. So, readers, if you want to create a new service or application in any medium, this testing is a must-have.

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