Concept Guides
Software Testing & QA Tools
The industry-standard tools teams actually use to test code — unit, end-to-end, API, and performance testing.
Jest
A zero-config JavaScript test runner with assertions, mocking, and snapshot testing bundled into one package — the default most React and Node tutorials assume.
Mocha and Chai
A test runner you assemble yourself: Mocha structures and runs the tests, Chai supplies the assertions — the flexible alternative to Jest's all-in-one bundle.
pytest
Python's de facto test framework: plain assert statements with readable failures, dependency-injected fixtures, and a plugin ecosystem that reaches into nearly every Python tool.
JUnit and TestNG
Java's two mainstream test frameworks — JUnit's annotation model that almost everyone learns first, and TestNG's more configurable alternative built for broader test scopes.
Playwright
A cross-browser automation library from Microsoft that drives Chromium, WebKit, and Firefox through one API, with auto-waiting built in to cut down on flaky tests.
Cypress
A JavaScript end-to-end testing framework that runs inside the browser alongside the app, trading some architectural reach for a fast, highly debuggable developer experience.
Selenium
The original, language-agnostic browser automation project, built on the W3C WebDriver standard it helped create — the widest reach of any E2E tool, at the cost of more manual setup.
Postman
A GUI API client that grew from a Chrome extension into a full platform for building, testing, and documenting APIs.
Insomnia
An open-source desktop API client for designing and debugging REST, GraphQL, WebSocket, and gRPC calls, now developed by Kong.
REST Assured
A Java DSL that lets automated REST API tests read like a sentence: given a request, when it's sent, then assert on the response.
Apache JMeter
The GUI-first, XML-based load testing tool that predates almost every alternative, with protocol coverage that goes well past HTTP.
k6
A code-first load testing tool: JavaScript test scripts, a lightweight Go engine, and pass/fail thresholds built for CI/CD.