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Top 12 Best API Testing Tools for 2023 and Beyond

12 API Testing tools
Posted On: 1 December 2023

APIs enable computer programs to interact with each other. Further, API testing is involved to verify the entire system's functionality. As such, API testing allows development teams to test an application's essential functions earlier in the process. So, API testing is a crucial step in the development process as it helps to streamline the process, optimize efficiency, and avoid potential pitfalls. API testing is also integral to system verification and should be checked before we put the API in production. It helps to ensure that its interfaces are working correctly.

Testers can either manually or automate API testing. In that case, teams can choose the tools based on their testing requirements. Hence, whether you are an experienced or a fresh professional, this blog will provide a list of the best API testing tools to assist you in choosing an appropriate tool for your product or business needs.

API Testing tools comparision table

Review Of 12 API Testing Tools In The Industry



ACCELQ provides continuous testing solutions for functional and API testing needs. It supports RESTful Web Services and Microservices and is available as both SaaS and on-premise models.

The platform's analytic runtime engine with advanced multi-step heuristics can detect changes to application elements and automatically adapt to ensure reliable test executions. ACCELQ provides 360-degree quality coverage by embedding critical server-side API validations alongside front-end testing. So, users can quickly verify response times, status, occurrence, header values, content, and more through a wizard-based approach.

Moreover, the continuous action dashboard also provides an overview of the software development lifecycle (SDLC) status, allowing users to visualize failure density and patterns easily.


  • It is a Unified platform for API, mobile, and web continuous testing.
  • This platform integrates with DevOps tools like JIRA and Bamboo.
  • API Test Automation is executed with Zero code on the Cloud.
  • Accelq performs API and UI Test Automation in the same simplified flow.
  • This platform directly correlates business processes and corresponding API for complete coverage.
  • The platform provides RESTful Web Services and Microservices.
  • The APIs need regression-level test automation maturity. As a result, this platform automates APIs with automated test design, codeless automation logic, complete test management, planning, and 360 tracking.

2. Assertible

Assertible Logo

It is a popular tool among API developers. Assertible automates API testing at every phase, from continuous integration to delivery pipelines.


  • This tool performs API test automation across the CI/CD pipeline.
  • This tool supports validating HTTP responses using turn-key assertions.
  • Assertible has an encrypted variable feature for storing passwords, tokens, and confidential data fields.
  • Easy to integrate with tools like GitHub, Zapier, Slack, and more.

Website Link:

3. API Fortress


API Fortress is an open-source platform for API testing. With this tool, teams can automate performance and functional testing. It is highly recommended for REST and SOAP monitoring.


  • User-friendly and intuitive UI for any user.
  • Plug-and-play functionality for simulating API testing.
  • Web-based tool using which software testers can perform API testing in any browser.
  • This tool supports microservices, web services, SOAP, and GraphQL.

Website Link:

4. Hoppscotch


This open-source API testing tool is an ideal replacement for the Postman tool. With its minimalist UI design, Hoppscotch can generate API requests quickly, thus saving valuable development time.


  • Full-duplex communication using a single TCP connection
  • Data transmission and receiving using the SocketIQ server
  • This tool supports REST, GraphQL, and Realtime protocols.
  • REST and GraphQL protocols have environments, collections, and history features.
  • An environment helps us create variables to reuse in scripts. Environments are also helpful when managing shared data with a team.
  • Hoppscotch helps in organizing API requests with collections. Create collections and add requests to them to share with the team or to use later.
  • This tool helps to keep track of API requests and responses. We can access the history of requests by clicking on the “History” icon on the Workspace side panel.

Website Link:

5. JMeter

JMeter Logo

JMeter is an open-source Java application that tests applications' functional behavior and performance. The JMeter's primary purpose is to test web applications. In addition to supporting caching and offline test results analysis, JMeter can also replay test results. However, Apache JMeter cannot perform all the actions supported by browsers, as it is not a browser but works at a protocol level.


  • This tool supports test results offline replay.
  • JMeter is compatible with both static and dynamic resources for improving test performance.
  • Ability to load and perform testing in various applications/server/protocol types, namely SOAP / REST Web services, Java Objects, and more.
  • This tool is compatible with languages like Groovy and BeanShell.
  • Data analysis and visualization plugins of this tool allow extensibility.
  • Functions can be used to provide dynamic test inputs.
  • This tool integrates through third-party open-source libraries for Maven, Gradle, and Jenkins.

Website Link:

6. Katalon Studio

Katalon Logo

Katalon is a powerful management platform that caters to a wide range of testing requirements such as web, API, mobile, desktop, AI visual, and enterprise applications. The platform supports Behavior-Driven Development (BDD) by a native Gherkin editor. In addition, Katalon allows importing Cucumber files and import tests from other API testing tools.


  • Katalon supports REST, SOAP/1.1, and SOAP/1.2 requests.
  • Tests can be imported from Swagger, Postman, and WSDL.
  • This platform performs data-driven testing with multiple data sources (e.g., XLS, CSV) and databases.
  • Katalon also supports BDD with Cucumber files and a native Gherkin editor.
  • Enable CI and DevOps practices with built-in integrations. Easy deployment with Docker containers.
  • Local and remote execution with real-time analytics.

Website Link:

7. Karate DSL

Karate API Logo

It is an API testing tool that allows users to create scenarios for API-based tests without writing the definition steps. Instead, Karate DSL makes the definition steps automatically to accelerate the API testing process.


  • Asynchronous support for WebSocket
  • Built on top of the Cucumber JVM
  • This tool creates test cases using a Gherkin-like BDD syntax.
  • The option to invoke via a Java API means that the tool can combine Java projects or legacy UI automation suites.

The latest version, 1.2.0 of Karate, supports a host of added functionalities like redesigned HTML reports, single-call caching, and tree walking in UI testing.

For instance, imagine a website or an app's interface as a tree. The "tree" has various "branches" (like menus, buttons, forms) and "leaves" (like text fields, checkboxes, links). Tree walking in UI testing involves systematically going through the branches and leaves to ensure the app functionalities work as expected.

Website Link:

8. Postman

Postman Logo

Postman is a versatile platform that helps in building and utilizing APIs. It streamlines all phases of the API lifecycle, enabling superior APIs. In addition, Postman provides a range of automated API testing tools, workspaces, and integrations that simplify the development process. Postman Flows is a low-code tool that creates API workflows, integrations, and automation in a collaborative environment without coding.


  • It is compatible with Google, Mac, Linux, and Windows systems.
  • The platform supports writing Boolean test cases (without a command line.)
  • It has a collection of built-in testing tools and workspaces.
  • Postman’s API Builder helps to implement an API design workflow through OpenAPI, GraphQL, or RAML specifications.
  • The Private API Network of this tool supports versioning to maintain control and manage multiple versions of APIs in the network. In addition, APIs can be organized into hierarchical folders to mirror your organizational needs.

Postman Flows is a new low-code tool for building API applications. It creates workflows, integrations, and automation in a collaborative environment—without writing a single line of code.

Website Link:

9. Ready API

Ready API

It is a popular functional testing tool suitable for API testing. Among its main capabilities, this API testing tool allows testers to test SOAP and REST APIs and web services quickly.


  • This tool provides detailed end-to-end testing to chain together complex API transactions and workflows. It creates testing suites that can be run in a CI/CD environment.
  • With a click, ReadyAPI can add security scans to new or existing functional tests.
  • Import data from a file or database or create synthetic data easily with ReadyAPI Data Generator.
  • Synthetic data helps test new programs without actual user data in software testing. As a result, it keeps information confidential and is a safer alternative for most application development.
  • ReadyAPI easily integrates with native plugins, other popular tools, and Command Line Interface.
  • Measure the test coverage of the entire API by importing OpenAPI Specification (fka Swagger) into ReadyAPI.

Website Link:

10. Rest Assured

Rest Assured Logo

Rest-Assured is an open-source Java tool designed to simplify the process of testing REST interfaces. It verifies complex HTTP responses within applications, supporting JSON and XML formats.


  • Behavior-driven development (BDD) that simplifies API testing in Java
    Seamless integration with Serenity automation framework
  • Built-in functionalities so that users don’t have to create test cases from scratch
  • A single framework that combines REST services and UI

The most recent version of Rest Assured, as of 8th September 2023, is 5.3.2, which includes several bug fixes, better Spring MockMvc Support, and improved compatibility with newer versions of Spring Security.

Website Link:

11. SoapUI

SoapUI Logo

SoapUI is a versatile open-source testing tool that covers the complete testing requirements. Its user-friendly interface makes it the preferred choice for hassle-free REST, SOAP, and GraphQL-based web service validation. With SoapUI, you can ensure that your web services meet the required functionality, performance, and security standards across different protocols.


  • The tool has a drag-and-drop feature to create and run complex scenarios.
  • Using a complement of tests and scans, it protects the services on websites against the most common security vulnerabilities.
  • Create load tests quickly and easily based on existing functional API tests.
  • This tool doesn’t require expensive full-scale replicas of your production systems.
  • This tool supports SOAP/WSD, REST, GraphQL, and JMS protocols.

Website Link:

12. Swagger

Swagger Logo

Swagger is a suite of API testing tools that facilitate the entire API development lifecycle, from design to deployment. Individual developers, as well as teams, can use the tool. SmartBear Software develops it.


  • Before any code is written, Swagger tools allow teams to design API interfaces. Creating and testing the API structure ensures the requirements are met and logically consistent before implementation.
  • Swagger includes schema validation. It can automatically ensure that the requests and responses of the API match the defined schema. This tool maintains consistency and reliability in API responses and requests.
  • Swagger tools integrate with popular API development frameworks. This integration streamlines the workflow from design to testing, making it easier to maintain and test APIs throughout the development lifecycle.

Website Link:

Geosley Andrades

Director, Product Evangelist at ACCELQ

Geosley is a Test Automation Evangelist and Community builder at ACCELQ. Being passionate about continuous learning, Geosley helps ACCELQ with innovative solutions to transform test automation to be simpler, more reliable, and sustainable for the real world.

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