Most API test tools ask you to write a program. You set up a Java project, import a library, define classes and methods, and inside all that scaffolding you finally make an HTTP call and assert something about the response. It works, but a lot of the work is ceremony that has nothing to do with the test you actually wanted to write. Karate's whole pitch is to delete the ceremony.
Gherkin, but without the glue code
Karate is built on top of Cucumber, so tests are written in the same plain-English Given/When/Then style, in .feature files. But it does something Cucumber pointedly does not: it drops the step definitions. In normal Cucumber, every "Given I call the login endpoint" has to be wired by hand to a Java method that actually does it — the glue code. Karate ships that glue for you. The DSL already knows what "make a GET request," "set this header," and "the response status should be 200" mean, so you write the test directly and there's no Java layer underneath to maintain. That single decision — Gherkin with the step definitions already built in — is the thing that makes Karate feel different from everything around it.
What that buys you
The headline consequence is accessibility. Because you're writing plain-text steps and not Java, someone who isn't a strong programmer can read and write real API tests, which is rarely true of code-first tools. On top of that, Karate bundles things you'd otherwise assemble yourself: first-class JSON and XML assertions so you can match a whole response shape in one line, built-in parallel execution, service mocking, and even performance testing — all in the same tool and often the same file. The usual figure quoted is around sixty percent less code than the code-first alternative, and while I'd treat any such number with suspicion, the direction is right: there is dramatically less of it.
Karate versus REST Assured, honestly
The natural comparison in Java land is REST Assured, and the trade is clean. REST Assured is a library — a fluent Java API you embed in a normal Java project, which means you get the full power of the language: loops, conditionals, any dependency you like, arbitrary logic. Karate is a framework that replaces the Java with its own DSL. So REST Assured wins when you need real programmatic control or your team lives in Java anyway; Karate wins when you want fast authoring, built-in parallelism and mocks, and tests non-developers can touch. One practical detail worth knowing: REST Assured's own maintainers note it isn't fully thread-safe, while Karate was built for parallel runs from the start — which matters once a suite gets large.
The catch
And there is a catch, because the strength is the weakness. A DSL is wonderful until you need something it didn't anticipate. When your test logic gets genuinely complex — conditional flows, elaborate data manipulation — you're either reaching for Karate's embedded JavaScript or fighting the DSL's edges, and at that point the plain-English simplicity that sold you starts to leak. You're also learning a bespoke language rather than a general-purpose one; that knowledge doesn't transfer the way Java does.
So the honest verdict is the boring one. Karate is genuinely excellent for the large middle of API testing — straightforward request-and-assert scenarios, done fast, in parallel, readable by the whole team. It's not magic, and it's not the right tool when your tests need to be real programs. Knowing which kind of testing you're doing is, as usual, the actual skill.
