Karate DSL

Consumer-driven contract testing for APIs and microservices

Pact is the de-facto contract testing framework for HTTP APIs and event-driven systems across 12+ languages. It verifies that services can communicate correctly by testing API contracts from the consumer's perspective before deployment, catching breaking changes in microservice architectures. Maintained by Pact Foundation with 7,000+ combined GitHub stars across implementations. PactFlow offers a managed SaaS broker. Used widely in enterprise microservice teams to prevent integration failures.

Git-friendly offline API client

Open-source API client for testing REST, GraphQL, and gRPC APIs as a lightweight, privacy-focused alternative to Postman. Stores API collections as plain files in your Git repository for easy version control and team collaboration. Features environment variables, scripting, collection runner, and a declarative syntax called Bru. Offline-first with no cloud account required. Available on macOS, Windows, and Linux. 44K+ GitHub stars and growing rapidly among developers leaving Postman.

Modern load testing for developers

k6 is an open-source load testing and performance testing tool developed by Grafana Labs. Developers write performance tests in JavaScript and execute them on a high-performance Go runtime capable of generating thousands of virtual users per machine. Features a CLI-first workflow, cloud-based test execution, and integrations with Grafana dashboards — making performance testing as accessible as writing unit tests.

Test and debug MCP servers before they ship

Open-source platform for inspecting, debugging and regression-testing MCP servers, MCP Apps and ChatGPT apps, with OAuth and protocol conformance for local and CI workflows.

Open-source MCP bridge between AI assistants and the Unity Editor

MCP for Unity is CoplayDev’s MIT-licensed bridge between MCP-compatible AI assistants and the Unity Editor. It exposes tools for assets, scenes, GameObjects, scripts, tests, profiling, and build-oriented workflows. The community project supports Unity 2021.3 LTS through 6.x and is explicitly not affiliated with Unity Technologies.

Sentry-maintained MCP server and CLI for Xcode builds, simulators, and tests

XcodeBuildMCP is a Sentry-maintained, MIT-licensed MCP server and CLI for agent-assisted iOS and macOS development. It lets MCP-compatible coding agents run Xcode build and test workflows, manage simulators, inspect failures, and work through Homebrew, npm, or on-demand client configuration, with documented Sentry telemetry controls for teams that need an opt-out.

Open-source diagnostic for AI operational misalignment

iFixAi is an Apache-2.0 diagnostic tool for scoring AI agents and models against operational-misalignment risks such as hallucination, manipulation, sabotage, sandbagging, and oversight evasion.

UK AI Security Institute framework for LLM safety evaluations

Inspect AI is an MIT-licensed framework from the UK AI Security Institute for running large language model evaluations, including tool use, multi-turn dialogue, model-graded scoring, and reusable evaluation tasks.

Apple's Safari-native MCP server for web debugging agents

Safari MCP Server is Apple's safaridriver-based MCP server in Safari Technology Preview, giving compatible coding agents local access to Safari page content, console logs, network requests, screenshots, JavaScript evaluation, interactions, viewport controls, and accessibility/performance checks.