11 Best API Testing Tools

Application programming interface(API) is a collection of software functions and procedures through which other software applications can be accessed or executed. In case of API testing, you use software to send calls to API, get output and log system’s response. As shorter development cycles put more pressure on automated testing, API testing becomes more important for agile development. So here we’ll see the top 15 API testing tools that you can use in 2021. But before digging to it, let us see what is API testing is software and need of API testing.

What Is API Testing In Software Testing?

Testing API becomes an important part of complete software testing. It creates a second layer of testing and requires nearly 20% of testing efforts. As there is no GUI, API testing is done at a message level. It includes testing soap web services, REST API’s. Due to the API testing characteristics, it cannot be manually done, and so there comes the need of API testing tools for automated API testing. Various kinds of testing is done during API testing such as- functionality testing, security testing, reliability testing, load testing, API documentation testing and proficiency testing.

Need Of API Testing-

• Core functionalities of API can be validated
• Consumes less time than that of GUI functioning testing
• Test data is mostly derived as JSON or XML. So the process, not language dependent
• Analysing app at API level would be catastrophic so it is better to do it at first

Top 11 API Testing Tools-

1. Katalon Studio-

It is a free test automation tool which is compatible with API, Web and Mobile apps, and is rapidly increasing its scope as a best tool for API API/Web services testing by being the comprehensive solution developers and testers need. This tools supports SOAP and REST requests, range of commands and parameterization functionalities they need. Also it has the  ability to combine UI and API/Web services to function in various environments like macOS, Linux, Windows and this is a unique feature among best API tools. 

Features-

• It can be used for both exploratory testing and automated testing
• Supports CI/CD integration and AssertJ by allowing for a fluent assertion with BDD style.
• Covers API, WebUI and mobile testing and their features
• Supports data centric approach
• It also supports SOAP and REST both
• Can accessible to non-tech savvy people and also professionals with both Manual and Groovy Scripting modes

2. Soap UI-

It is a popular API testing tool for functional testing that allows automation testing of SOAP, REST APIs, and web services. SOAP UI has a free version and a pro version, where pro version offers more features than free version. Here are some of the features of SOAP UI- 

Features-

• Seamless integration- Integrates with 13 API management platforms, supports REST, SOAP, JMS and IoT
• Powerful data-driven testing- Load data from Excel, files and databases to simulate the way users interact with your APIs.
• Essay test creation- Point-and-click, drag and drop,functionality make complicated tasks easy
• Script reusability- Reuse functional test cases as load tests and security scans in few clicks.

3. Apigee-

It offers benefit of allowing users to access its features by using other editors. Users can test performance and build API using other editors like Swagger while using the Apigee tool.

Features-

• Allows easy creation of proxies from Open API Specification
• It can track API traffic, response times, as well as error rates
• Identifies performance issues
• Useful for digital business and data-rich mobile driven APIs
• Supports cloud, on-premise, or hybrid deployment model

4. Parasoft SOAtest-

It builds automated tests that can be executed as a part of continuous integration and DevOps pipelines. This tool automates the continuous testing of complicated systems by creating codeless API test scenarios from manual recordings. It has ability to transform your test artifacts into security and performance tests, increasing reusability and reducing redundancy.

Features-

• Synchronizes test assets in sync with evolving systems via automation
• Uses AI to create test scenarios rapidly
• Easily integrates with load testing and service virtualization
• Automatically generate codeless API tests that are easy to share, reuse and robust 

5. Postman-

It is a popular API automation testing tool among testers who want to evade coding in IDE by using development language. Some of the great features are as follows-

• Simple to use with Rich interface
• Supports windows, Linux, chrome apps and Mac
• Supports automated and exploratory testing
• Postman offers run, test, document and monitoring features
• Supports GRAPHQL request and GRAPHQL variables, schemas and GRAPHQL query auto-completion function

6. Tricentis Tosca-

It is a robust web services testing tool for Agile and DevOps. Some of the popular features are-

• Integrates into Agile and DevOps cycle
• It uses model-based test automation that makes script maintenance simple
• As API tests can be used across mobile, cross-browser, packages apps, it enables end to end testing 
• It supports a lots of protocols including AMQP, Rabbit MQ, HTTP(s), REST, IBM MQ, NET TCP, TIBCO EMS, SOAP etc.

7. API Fortress-

It is a powerful monitoring tool for SOAP APIs and REST. It is popular for its simplicity,  and some of its features are as follows- 

• Compatible with cloud 
• Offers easy test generation with one click
• Data integration and great notification
• Simple UI

8. HttpMaster-

This tool is used to automate web app testing, including API testing, service testing and website testing. HttpMaster is a best testing tool that mainly used as web API test tool to automate testing of web API calls. Some of the best features are as follows-

• Efficient command-line interface
• Supports request data builder and response data-viewer
• Offers custom verbs, defined global parameters
• Supports customized API requests
• It is compatible with swagger

9. Ping API-

It is an API testing tools that allows you to write test script in Javascript and CoffeeScript to test your APIs and also allows inspecting HTTP API call with complete request and response data. In case of any failure, user gets a notification through email, slack or Hipchat.

Features-

• Validates CRUD flow and log in to Ping API
• Supports to write script to set request headers, body and URL parameters, writing script to validate response headers and body

10. Karate DSL-

It focuses on creating scenarios for tests in a simple way. There is no need to write step definitions, as KarateDSL creates them for quick start. Some of its features are as follows-

• Creates reports like Java projects
• Easy to learn for novices
• Offers support for multi-threaded parallel execution

11. Hippie-Swagger-

It is a tool used to test APIs that supports clear assertion syntax, for extending test behavior. It also allows clean printing reports. Some of the features are as follows-

• Readable and accurate assertion messages
• Validated parameters, requests, response, pats etc.