Writing API tests usually means writing code — assertions, fixtures, setup and teardown in whatever language your backend uses. A smaller category of tools instead lets you describe a test as a plain-English sentence ("Given the user is logged in, When they call /orders, Then they get a 200") that a non-developer on the team can actually read. RestQA and Karate both work this way, both are free and open-source, and each lists the other as its closest alternative — the difference is how much they try to cover beyond that core idea.
RestQA: does one thing, stays out of your way
RestQA is scoped deliberately narrow: API testing only, written in Gherkin syntax that a QA lead or product manager can read without knowing the codebase, plus automatically generated API documentation and test coverage reports. It's 100% free with no paid tier at all. The target user is explicit — backend engineers, tech leads and QA professionals who want microservice tests the whole team can review, not just the person who wrote them.
The honest limit: RestQA's scope is genuinely narrower than Karate's (API testing, full stop — no UI or performance testing), and its community is smaller, which means fewer plugins and less documentation to lean on when you hit an edge case.
Karate: one framework instead of four
Karate covers more ground — API tests, mocked services, UI automation and performance testing, all written in the same plain-English style, so a team doesn't need to stitch together separate tools for each concern. It backs that up with real scale: 8,800+ GitHub stars and over 2 million downloads a month, plus a claimed ~60% reduction in test code volume versus writing assertions by hand. The open-source core is MIT-licensed and free; Enterprise add-ons (Karate Agent, Xplorer, dedicated support) are quoted on request.
The tradeoff: Karate runs on the JVM, which is overhead for a team with no Java in its stack, and the learning curve is steeper than a point-and-click tool like Postman — you're trading a GUI for scriptable, version-controllable tests.
Side by side
| RestQA | Karate | |
|---|---|---|
| Scope | API testing only | API + UI + mocks + performance |
| Pricing | 100% free, no paid tier | Free core (MIT) + quoted Enterprise add-ons |
| Runtime | Lightweight, no JVM requirement | JVM-based |
| Community | Smaller, fewer plugins | 8,800+ stars, 2M+ downloads/month |
| Best for | Teams wanting a minimal, readable API-only tool | Teams wanting one tool for API, UI and perf testing |
Pick RestQA if… / Pick Karate if…
Pick RestQA if you only need API tests and want the smallest possible tool doing exactly that — no JVM, no UI-testing features you'll never touch, just readable Gherkin scenarios against your endpoints. Pick Karate if you'd rather consolidate API, UI and performance testing into a single framework with a large, mature community behind it, and you're fine with the JVM dependency and steeper learning curve that comes with it.
The honest bottom line: both explicitly name each other as their main alternative, and for good reason — the plain-English testing philosophy is identical. The real decision is scope. If your team is only ever going to test APIs, Karate's extra surface area (UI automation, performance testing) is dead weight you're carrying for nothing; if you're likely to need those things eventually, starting with Karate avoids a second migration later.