10 API Testing Tools to Try this Year

According to Zion Market Research, Global API Management Market to Register $3,436.16M Growth by 2022

APIs are becoming an integral part of how a software works. The more we rely on web-based systems, the more crucial it is that the API Testing is done properly and are available for consumers.

In this post, I will outline 10 API testing tools you should try this year.

API Testing tools are divided into two categories,

Hosted & Open-source

  • Open source API testing tools
  • Hosted API testing tools (free and paid)

Open source API testing tools


It is a famous open-source testing tool for web services testing as well as API testing. SoapUI’s functionality is mainly used for web service check, invoking, development, simulation and mocking, load testing, compliance testing and functional testing services.

Dredd (Command-line)

This is a command-line tool especially to validate an API based application on a formal definition like Swagger or API Blueprint.

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The tool is capable of validating responses against expectations defined in the specification.

This command line tool is seamless to perform API testing from a CI/CD pipeline and also it supports defining advanced tests in many programming languages including ‘Go’ and ‘Python’.

Swagger-test-templates (Command-line)

This is a code generator used to generate API test-suites depending on a Swagger definition. It also generates test suite’s code in Javascript using familiar libraries such as Mocha JS, Chai JS, and Commander JS.

Karate DSL (Command-line)

Karate is a testing framework, which uses a BDD i.e. Behaviour-Driven Development, the domain-specific language for defining API tests.

Karate is built on top of the Cucumber-JVM which should make it familiar to anyone used to using Cucumber for BDD tests.

The main advantage of Karate is that it seamlessly supports the integration of CI / CD pipelines and can support testing live environments like dev, QA, or pre-prod. Karate has very comprehensive support for common HTTP calls that use SOAP/XML, HTTPS, HTTP proxies, URL-encoded form data, multi-part file uploads, and more.


This open source tool is widely used for API testing, despite the fact that it was designed for other purposes.

  • Results can be replayed.
  • Allows checks to be used in CI pipelines.
  • Both static and dynamic resources are supported.

API Fortress

API Fortress specifically targets REST and SOAP APIs, and remains the most powerful monitoring tool for the two. Known for its simplicity, API Fortress has already successfully enticed many enterprises to make the switch.

  • Offers easy test generation with one click.
  • Compatible with the cloud and with physical hardware.
  • Amazing notification and data integration
  • Simplistic UI for beginners

Rest Assured

Rest-Assured is a language that allows users to quickly evaluate REST services, as the name implies. It comes with a plethora of built-in functions to help you get started coding quickly.

  • Users are not required to have extensive HTTP expertise.
  • Serenity automation system compatible
  • Allows UI and REST tests to be integrated in one setting.


Assertible is an API testing tool that focuses on reliability and automation. This tool also supports HTTP response validation with turnkey assertions such as JSON Schema validation and JSON Path data integrity checks.

One major advantage of Assertible is its support for automating API tests through each step of a continuous integration and delivery pipeline.

It also supports running API tests after deployments and integrates with familiar tools like GitHub, Slack, and Zapier.

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Postman is a GUI API Testing client that supports exploratory testing, documentation, sharing and monitoring.

Even though Postman is a competing product with Assertible, it is a very strong product and has a wide set of nice features for API testing.

One big advantage of using Postman is that it runs on the local machine, which allows control of data. Some companies follow security restrictions which may prevent using a fully hosted option. Postman also supports running tests in a continuous integration pipeline using Newman.

Apigee API Studio

APIGee’s API Studio is for constructing APIs, which has few neat features designed to make testing easier. One can try this operation for API Response Simulation with mocked HTTP responses.

API Studio is still in Beta so it is expected that the producers will release even more API testing features.