karate

Karate is a single tool for API tests, mocks, performance tests, and UI automation. Tests read like English (Given/When/Then) so non-programmers can contribute without learning Java. MIT-licensed, the framework itself is completely free.

Runs on the JVM, which means JDK 8+ and Maven or Gradle in your pipeline. No separate test runner, no step definition files like in vanilla Cucumber, no Selenium WebDriver contortions. A test is a .feature file that hits an endpoint, asserts the response, and moves on. Mocking HTTP services is built in, so you can spin up a fake dependency in three lines.

QA teams with a mix of engineers and non-engineers get a language they can both write. Devs using Java/Kotlin/Groovy stacks get something that fits their build system. Karate Labs sells training and an enterprise UI layer, but the open source tool does the full job.

The catch: the DSL looks like Gherkin but is not. You cannot share feature files with a standard Cucumber pipeline, and if your team is already deep in REST Assured or Playwright, switching frameworks to get slightly better readability rarely pays for itself.