API Testing Tools

Published: 02 Feb 2023

Top 10 API Testing Tools in Software Testing Industry

Last Updated: 04 Oct 2023

Significance of API Testing Tools

API Testing Outlook in 2023

As more and more organizations in the United Kingdom (UK) turn to Application Programming Interfaces (APIs) to integrate their applications with other systems and environments, API testing is expected to be an essential part of software development in and beyond 2023. Api Testing Tools focuses on validating APIs’ functionality, performance, security, and reliability. The process also involves testing for compatibility with various browsers and devices.

As APIs become increasingly complex regarding features and functionality, testers in the UK must develop sophisticated test plans that cover all aspects of the API. The use of API testing automation tools is also expected to increase significantly in the coming years. Automated tests help reduce manual effort and improve test case coverage by running tests quickly across multiple environments. API testing tools also help detect errors earlier in the development process, reducing costs associated with fixing bugs later in the cycle.

Benefits of API Testing in Agile

Benefits of API Testing

API testing is an essential part of agile software development. It helps to ensure that the application is functioning as expected and allows developers to detect any issues that may arise during development quickly. Here are some key benefits of API testing in an agile environment:

Promotes Automation:

API testing is an ideal candidate for automation, saving manual testing time and effort. Automated tests can be run more frequently, allowing for faster feedback and quick fixes to any issues that may arise.

Improves Quality:

By testing APIs early and often, developers can quickly identify problems before they become significant issues. This helps to ensure a higher quality product is delivered on time and within budget.

Quickens Dev Cycles:

By running automated tests regularly, the Dev team can reduce the amount of time needed for debugging and bug fixing, resulting in shorter development cycles. This also helps to reduce costs associated with rework or delays due to bugs or compatibility issues.

Increases Team Collaboration:

API testing encourages collaboration between different teams, such as testers, developers, and operations personnel, who all need to work together to deliver a successful product on time.

Thorough Testing Coverage:

API testing provides comprehensive coverage of the application’s functionality and performance which helps to ensure that all areas of the system are tested thoroughly before it goes live.

Data Driven Testing:

Data-driven testing in API testing is a technique that involves using various sets of test data to validate the functionality, performance, and reliability of an API. With data-driven testing, testers can create multiple test cases that cover different scenarios and variations, allowing for more comprehensive test coverage.

Key Features to Look for in an API Testing Tool

feature of API testing tool

Automated Testing:

API testing tool should be able to automate the testing process, allowing you to quickly and efficiently test your APIs. Automation helps reduce the time and money spent on manual testing, allowing you to focus on other aspects of product development.

Comprehensive Reporting:

A good API testing tool should provide extensive reporting capabilities that allow you to quickly analyze the results of your tests and identify any potential issues or areas of improvement. This will enable you to make informed decisions about improving your APIs.

Cross-Platform Support:

As more applications move towards a multi-platform approach, an API testing tool must support multiple platforms, including web, mobile, and cloud-based services. This ensures that your APIs are tested across all platforms and can work seamlessly with other services and products.

Security Testing:

Security is an essential part of any application or API service, so an API testing tool needs to include security tests in its suite of features. These tests should ensure that the APIs are secure from malicious attacks and protect user data from unauthorized access or manipulation.

Ease of Integration:

The best testing API tools should be easy to integrate with existing systems and processes, allowing developers to quickly set up tests without having to learn a complex new language or system architecture. This makes it easier for developers to start their projects quickly and ensure that their APIs are appropriately tested before launch.

Non-technical Friendly:

The API testing tools’ documentation should feature support for BDD conventions, enabling even the non-tech savvy stakeholders to understand the project details via easy-to-understand reports.

Top 10 API Testing Tools in Software Testing Industry

Following are some of the tools for testing API that QA engineers use:

API testing tools

Katalon Studio

Katalon Studio is an automated testing platform that helps users create comprehensive end-to-end tests quickly and easily with its integrated environment for API, Web UI, mobile app testing, and cross-browser compatibility testing.

Tricentis Tosca

Tricentis Tosca is an enterprise-level API test automation solution designed to help users create reliable tests faster than ever before by taking advantage of model-based test automation technology combined with AI-powered analytics capabilities.


Postman is a popular tool that automates API testing. It is one of the API loading testing tools that allow users to easily create complex requests, save them for reuse, and share them with others. It also includes features such as automated tests, response data validation, environment variables, and more.


It is an open-source web service testing tool ideal for service-oriented architectures (SOA) and representational state transfers (REST services). It provides complete test coverage, from functional to security testing, and supports all major protocols, including SOAP/WSDL, REST/JSON, and GraphQL.

Apache JMeter

Apache JMeter is an open-source load and performance testing tool used to analyze the performance of web applications under various load types. It can be used to simulate a heavy load on a server or network to test its strength or analyze overall performance testing under different load types.

Parasoft SOAtest

Parasoft SOAtest is an automated and open-source API testing tool designed to help organizations ensure the quality of their services through comprehensive functional, security, performance, regression & compliance tests across multiple environments & protocols with minimal effort & cost associated with manual QA processes.

Rest Assured

Rest Assured is an open-source Java library that can be used to automate RESTful Web Services using JSON or XML payloads to perform functional validation on the response received from the server-side application over the HTTP protocol(s), including secure HTTPS requests.


Apigee is a cross-cloud API platform that enables developers to quickly design, deploy, secure, monitor, analyse and scale APIs. The platform provides tools for debugging, mocking, traffic management, quota management, analytics, etc.


Runscope provides a suite of API monitoring tools that allow developers to check uptime and performance metrics like latency & throughput as well as run end–to–end API tests. The tool also allows teams to collaborate on API development & troubleshooting.


Assertible provides continuous integration & deployment tools designed explicitly for API tests. The platform allows users to set up automated integration & regression tests which can then be monitored in real-time using dashboards & alerts.


API testing has become an essential part of software development in the United Kingdom and is expected to continue to grow in importance beyond 2023. It involves conducting performance, security, reliability, and functionality testing of APIs and their compatibility with various browsers and devices.

Today, the advancement of technology has led to apps becoming more complex in their architecture, featuring multiple layers. To ensure that these apps function correctly and provide a positive customer experience (CX), API testing must be conducted to validate different business layers to guarantee seamless applications. Digital businesses should seek services from next-gen testing service providers for fully functional business applications.

How Can TestingXperts Help Digital Businesses with API Testing?

How Can TestingXperts Help Digital Businesses with API Testing

TestingXperts (Tx) is one of the fifth largest global pure-play software testing services providers. Tx has been chosen as a trusted QA partner by Fortune companies and ensures superior testing outcomes for its global clientele. We have rich expertise in enabling end-to-end testing services for international clients across various industry domains like healthcare, telecom, BFSI, retail & eCommerce, etc.

API Testing Services Offered

Unit testing

Utilized to check the functionality of individual APIs.

Functional testing

Employed to test end-to-end functionality of the API layer.

Load testing

Validates both functionality and performance for the system under various levels of user/transaction load.

Runtime error detection

Involves executing automated or manual tests to identify problems, such as exceptions and resource leaks.

Security testing

Includes a variety of security checks, such as penetration testing, authentication, encryption, and access control.

Web UI testing

Entails end-to-end testing of the entire system using APIs.

Contract testing

Used to check the interaction between client and API or server and to verify data exchanges between two parties.

Why Choose Testingxperts for API Testing Services

TestingXperts is a Katalon Solution Partner Program member, enabling clients to deliver high-quality software faster by leveraging comprehensive DevOps and testing practices.

Team of expert API testers with expertise in various protocols, including XML, SOAP, JSON, REST, Gdata, YAML, ATOM, RSS and RDF.

QA engineers experienced in performing end-to-end application validations at all application levels.

Certified team with extensive knowledge of code-level functionalities to ensure high test accuracy.

Hands-on experience with industry-leading open source and commercial.

Our custom test execution report provides stakeholders with a rich interface for easy access to results. Lastly, we partner with renowned organizations such as UiPath, Tricentis, AccelQ, EggPlant, and more.

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