APIDog is a good alternative to Postman for a fraction of the cost, providing all the paid features of Postman.
Insomnia is an open source tool for API testing that offers a modern user interface and key functionalities like setting headers and parameters.
SoapUI is tailored for testing SOAP and REST web services, making it useful for those working with enterprise applications.
REST-assured is a Java library designed specifically for testing REST APIs through a fluent DSL.
K6 is an open source performance testing tool for APIs allowing developers to create and run tests in JavaScript.
Apache JMeter is a commonly used tool for performance and load testing of APIs.
Hoppscotch is a web-based API client that is lightweight and easy to use, allowing for quick and efficient API testing with its intuitive user interface.
Restlet Client is a versatile API testing tool that can connect to multiple types of services with features like real-time response display.
DHC is a Chrome app for API testing that is fast and easy to use and suitable for small to mid-scale applications.
Curl is a powerful command-line utility for making API calls, despite not being a graphical API client like other tools.