Open source. Open possibilities.

Storybook is a frontend workshop for building, documenting, and testing UI components and pages in isolation. It supports many frameworks and offers addons for accessibility, documentation, and interactive development.

A complete, serverless and distributed load testing platform for production-grade performance testing of APIs and browser-based workflows.

Robot Framework is a generic open-source automation framework used for acceptance testing, acceptance test-driven development (ATDD), and robotic process automation (RPA).

Karate is an open-source test automation framework that unifies API testing, mocks, performance testing, and UI automation into a single tool.

Hypothesis is a property-based testing library for Python that generates random inputs to uncover bugs and edge cases, reporting the simplest failing test case for easier debugging.

TUnit-native math assertion library for .NET: fluent tolerance, sequence, statistics, linear algebra, number theory, and 3D geometry assertions generated into TUnit's Assert.That pipeline; AOT-compatible and reflection-free.

Quick is a behavior-driven development (BDD) testing framework for Swift and Objective-C, inspired by RSpec, Specta, and Ginkgo. It pairs with Nimble for expressive matchers and supports multiple Swift versions via CocoaPods or Swift Package Manager.

Hoppscotch is an open-source API development ecosystem providing a lightweight alternative to Postman and Insomnia for testing and designing APIs.

React Testing Library is a lightweight solution for testing React components, encouraging tests that mimic real user interactions for better maintainability and confidence.

QA Studio is an open-source, self-hostable test management platform for QA teams. It offers hierarchical test suites and cases, test run planning across environments, rich dashboards for results and trends, media attachments, and a full REST API.

Reel generates always-current demo films for web apps and CLIs from a YAML spec. It drives a real browser or terminal, records the actual flow, and renders GIF, MP4, WebM, storyboards, and interactive HTML compositions. Works via CLI, Studio UI, or Claude Code plugin. Fails CI when demos break.

ripr is a static mutation-exposure analysis tool that identifies changed behavior your tests reach but don't actually verify, without running mutation testing.

MCP Arcade is a command-line testing tool that runs a small catalog of experiments, called atoms, against MCP servers, judging results by the JSON-RPC wire and sandbox file changes rather than by tool descriptions or model prose.

Toxiproxy is a framework for simulating network conditions to test application resiliency and identify single points of failure in CI and development environments.

Playwright is a comprehensive framework for web automation and testing that provides a single API to drive Chromium, Firefox, and WebKit across Linux, macOS, and Windows.

Keploy is an open-source, language-agnostic API and integration testing tool that records real API calls, database queries and streaming events via eBPF, then replays them as tests and data mocks without code changes.

Faker is a Python package used to generate synthetic data for database bootstrapping, stress testing, and data anonymization.

A DuckDB compatibility harness for rudb. It verifies conformance through differential execution against a real DuckDB binary, weighted SQL coverage, storage format round trips, and C ABI checks.

A local Node.js CLI that scans ETH/USDC prices across Chainlink, Uniswap V2, SushiSwap, Curve and Balancer and, when a spread of 0.9% or more appears, triggers flash-loan arbitrage via a contract, with built-in wallet creation and management.

A comprehensive Node.js best practices guide covering project architecture, code style, testing, production, security, and more.