API Software Testing Services | API Software Testing Company
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API Testing Services

Be sure of the consistent and secure work of all integrated APIs

Years in the market



Software QA engineers





The use of Application Programming Interfaces, which are better known as APIs, is a real mainstream. Software engineers actively develop APIs and integrate third-party APIs into the software solutions that they build in order not to reinvent the wheel. These days, hardly can you find an app that would not contain at least one API. Actually, applications may have just a few APIs or even several hundred APIs. Some of them can be quite simple, others - pretty complicated. Still, each API needs to be tested in order to mitigate possible risks and ensure top-notch quality. API software testing entails a direct check of a developed API or a check of third-party APIs in the developed app in the course of integration testing. If an API doesn’t work well, it can immensely affect software quality and your business in general.

To ensure smooth work, robustness, and solid security of APIs, multiple aspects must be considered in the course of testing including data accuracy, data type, request status, returned error codes, etc.

If you have arrived at the decision to outsource API testing services, DeviQA is at your disposal. Our highly skilled QA engineers know everything about API in software testing, and they will leverage their deep knowledge and rich expertise to contribute to the excellent quality of your app.

Benefits of API Testing


Early bug detection

The fact that API testing can be executed even without GUI gives an opportunity to check certain business logic at the early software development stages.



This pro of API testing stems from the above-mentioned one. As long as API testing lets a QA team identify bugs early, a development team can fix them easily and quickly before they cause more serious issues in the developed app. Due to this approach, it is possible to save a ton of time and money.


Easy test automation and maintenance

API tests are ideal for automation. The thing is that such tests are stable because there is very little likelihood of endpoint and request parameter changes unless there is a global change in business logic.


Time efficiency

The execution of automated API tests is much faster than the execution of automated functional GUI-based tests. It is explained by the fact that it takes a lot of time to load and render UI elements as GUI-based tests run.


Mitigation of security-related risks

As long as API is becoming the most common cyberattack point, full-fledged API testing contributes to the app security on the whole and helps to prevent possible cyber penetrations via APIs in particular.


Higher test coverage

It is of utter importance to make sure that all software components including integrated APIs work according to specifications. Thus, API testing contributes to establishing good test coverage which, in turn, results in better software quality.

API Testing Types We Provide

DeviQA provides all common API testing types. Here are they:

API Functional Testing

This type of API testing checks whether an API works as it actually should work. In general, it refers to the evaluation of the API responses in terms of output accuracy and compliance with the defined parameters. Beyond that, functional testing also considers error handling.

API Performance Testing

It is essential to be confident in the ability of an API to efficiently handle the usual and high loads. For this purpose, performance tests are carried out. Particular attention is paid to load testing and stress testing.

API Security Testing

Unfortunately, APIs are often used as a loophole by cybercriminals. To mitigate the possible security risks and keep sensitive data securely protected, it is crucial to check APIs for compliance with the main security requirements including those related to authentication, permissions, and data encryption.

API Integration Testing

API testing can be defined as one of the activities or components of integration testing, so we check whether API communication and data exchange work as expected. Besides, integration testing also helps to make sure that all integrated APIs are connected and interact properly with each other.

API Fuzz Testing

This type of testing checks an API behavior in the worst-case scenario. It suggests forceable input of a massive amount of invalid and random data in order to bring about a crash, overflow, and other negative reactions.

Validation testing

Depending on the situation, validation testing checks whether a developed API really fulfills its purpose or whether chosen APIs are appropriate for a developed app.

Our API Testing Methodology

Our API testing process starts with a thorough study of API and its requirements. Our experts strive to clearly understand the main purpose of an API and its key functions and features. Besides, they reveal the place of the tested API in the app workflow and all other APIs with which it interacts. Attention is also given to the tech stack used on the project.

Then we turn to the planning phase. API testing process should be carefully planned. Our QA specialists define the scope of API testing and requirements for a test environment. Additionally, they decide on the most appropriate API testing tool or a set of such tools. We always try to automate API testing as much and early as possible.

After planning we get down to the preparatory works. A test environment is set up in accordance with the pre-confirmed requirements. The key goal is to make it as similar to a production environment as possible. At the same time test cases are written in order to be automated later. We create both negative and positive test cases.

As soon as everything is ready tests are executed and all the uncovered bugs are reported. Once the work on bug fixing is completed, we make sure that the issues have been indeed resolved.

If our Client has adopted DevOps practices, we integrate automated API tests into continuous testing and CI/CD server.

The Way We Provide Our API Testing Services

Whenever our Clients apply for an API testing service we arrange the work in accordance with the following algorithm:




Test Planning


Test documentation design


Test framework development


Test case design and test script writing


Test environment setup


Test execution


Test reporting

How we work when provide API Testing Services


Define tech stack that suites to the current project


Create test cases for all possible combinations to ensure that we complete full test-coverage of API.


Group test cases into categories


Declare all functions of tests


Make tests independent


Specify test data in the entity and not in tests themselves

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Types of defects that can be found during API Testing

At DeviQA, we apply a holistic approach to API testing and execute multiple tests to thoroughly check the most diverse aspects of API operations. As a result, our API testing service helps to detect a variety of defects including the following ones:

Failure to handle invalid conditions

Unused flags

Missing or duplicated functionality

API connection issues

Security issues

Performance-hindering bugs

Multithreading issues

Compatibility issues

False errors

Incorrect data structuring

Frameworks, Tools and Solutions

JMeter for API Testing


Postman for API Testing


SoapUI for API Testing






Why outsource API testing services to DeviQA?

DeviQA is a reliable provider of software testing services. API software testing is our forte. If you are interested in an API testing service, we can be your trusted partner. There are indeed a lot of reasons to entrust us with this mission.

Ample experience

DeviQA has taken on the most diverse projects and can boast of rich experience that lets us provide top-notch API testing services. Our brilliant QA specialists are familiar with diverse API protocols including REST, XML, SOAP, JSON, RSS, YAML, and others, and always provide comprehensive API testing.

An all-encompassing approach to API testing

We apply a holistic approach to API testing and check every single feature and aspect of API work. As a result, we provide the most comprehensive test coverage that an API testing service provider is only capable of.


In the pursuit to ensure great collaboration and provide our client with outstanding API testing services, we try to be flexible in all terms. We easily adapt to any time zone, used software development methodologies, corporate policy, etc. We are completely focused on the needs of our Clients and arrange our work in a corresponding way.

Use of the most advanced testing tools

We keep an eye on technology development and quality assurance trends. Therefore, in our work, we use the most cutting-edge tools and technologies that let us deliver awesome results and provide unmatched quality for your software product. A broad range of leading API testing tools is heavily used by our QA team. In each particular case, it chooses the most appropriate variant for efficient API testing.

Dedication to test automation and DevOps practices

DeviQA has seasoned automation QA engineers in place who can create stable automated API tests for your project and integrate the API testing suite into your continuous testing.

Popular Questions

When API testing should start?

It depends on which API testing you need to perform. A lot of applications used the so-called "internal" API to communicate between different parts of the application. We strongly feel that these API endpoints should be tested at priority instead of working on UI testing. The reason for that is that it is a core of the system, and it should work as designed.

Should we do manual or automation API testing?

From our point of view automation API testing is a must. Here are several points:


API automation tests do not depend on UI and are much stable comparison to UI tests


API automation tests development is much faster than UI automation


API automation test runs are blazing fast


API automation tests could be run even after each commit to indicate that API works with no issues

Can we integrate API tests to CI/CD tool?

We think that this is a must. Even if you have postman tests that should be done. It will give you the following benefits:


More visibility of test results for the team


Tests are running without human involvement


Continuous delivery process


Automation testing for each commit


Quick indication of the issue

We would like to order your API testing services, but we do not want to share codebase of our application. Is it possible?

Sure thing. For developing API tests, we do not need access to your codebase. Our API tests could live in a separate repository.

We are using the BDD approach on the project. Can you develop API automation tests in BDD style?

Of course, we can use Cucumber, Behat, Aloe, JBehave, and others.

What tools are you using for manual API Testing?

We prefer to use Postman as a tool for manual API testing due to the following reasons:


Easy to use


Could be integrated with CI/CD tool


Ability to storing test data through different environments


Ability to use variables

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