Karate

Karate is the only open-source tool to combine API test-automation, mocks, performance-testing and even UI automation into a single, unified framework. The BDD syntax popularized by Cucumber is language-neutral, and easy for even non-programmers. Assertions and HTML reports are built-in, and you can run tests in parallel for speed. There’s also a cross-platform stand-alone executable for teams not comfortable with Java. You don’t have to compile code. Just write tests in a simple, readable syntax, carefully designed for HTTP, JSON, GraphQL and XML. And you can mix API and UI test-automation within the same test script. A Java API also exists for those who prefer to programmatically integrate Karate’s rich automation and data-assertion capabilities. It is worth pointing out that JSON is a ‘first class citizen’ of the syntax such that you can express payload and expected data without having to use double-quotes and without having to enclose JSON field names in quotes.