Testing & QA

Unit and integration test runners and assertion libraries for Node.js, Bun and browser code.

Vitest, Jest, Mocha

The standard unit testing frameworks for major non-JavaScript ecosystems.

pytest, JUnit, xUnit.net

Frameworks that drive real browsers to test full user flows across the stack.

Playwright, Cypress, Selenium

LLM-driven tools that let agents drive browsers, generate tests from traffic or run natural-language test suites.

Playwright MCP, Browser Use, Stagehand

Tools for rendering and testing UI components in isolation, in simulated DOMs or real browsers.

Testing Library, Storybook, jsdom

Tools for testing HTTP/GraphQL APIs, verifying contracts between services and fuzzing from OpenAPI specs.

Postman, REST Assured, SuperTest

Libraries and servers for mocking functions, objects and network APIs so tests stay fast and isolated.

MSW, Mockito, WireMock

Tools for load, stress and benchmark testing of APIs and web apps.

k6, JMeter, Locust

Screenshot-diffing tools and services that catch unintended UI changes in review.

Chromatic, Percy, Applitools Eyes

Native and cross-platform mobile UI test frameworks plus cloud grids of real browsers and devices.

Appium, Espresso, XCUITest

Automated checkers and linters that catch WCAG issues during development and in CI.

axe-core, Lighthouse, eslint-plugin-jsx-a11y

Generate realistic test data and spin up real dependencies (databases, cloud APIs) for integration tests.

Testcontainers, Faker.js, Faker (Python)

Measure code coverage, publish test reports and track quality gates and flaky tests over time.

Istanbul, c8, coverage.py

Generate inputs automatically to find edge cases, measure test-suite strength and uncover crashes.

Hypothesis, fast-check, proptest