Awesome Harness Engineering

DeepSeek Harness: Everything is a Plugin.

The open source coding agent.

Build Agentic workflows, RAG pipelines, with rich AI model and tool support on one collaborative workspace. Deploy on cloud, VPC, or self-hosted, so teams move from prototype to production without rebuilding the stack.

AI agent toolkit: unified LLM API, agent loop, TUI, coding agent CLI

🙌 OpenHands: AI-Driven Development

Orca is the ADE for working with a fleet of parallel agents. Run any coding agent with your own subscription. Available on desktop, mobile and remote runtime.

Never stop coding. Free MIT AI gateway: one endpoint, 359 providers (150+ free), 1200+ models Kimi, Claude, GPT, Gemini, GLM, DeepSeek, MiniMax. Works with Claude Code, Codex, Cursor, OpenCode, Cline & Copilot. Quota-aware auto-fallback, RTK+Caveman compression saves 15-95% tokens, MCP/A2A, Desktop/PWA. Built by hundreds of contributors

Context7 Platform -- Up-to-date code documentation for LLMs and AI code editors

Chrome DevTools for coding agents

Teams-first Multi-agent orchestration for Claude Code

Playwright MCP server

🪢 Open source agent evals & observability: Trace, evaluate, and improve LLM applications with one open platform.

Composio powers 1000+ toolkits, tool search, context management, authentication, and a sandboxed workbench to help you build AI agents that turn intent into action.

Mastra is the modern TypeScript framework for AI-powered applications and agents.

A format specification for describing a visual identity to coding agents. DESIGN.md gives agents a persistent, structured understanding of a design system.

#1 Persistent memory for AI coding agents based on real-world benchmarks

The AI Toolkit for TypeScript. From the creators of Next.js, the AI SDK is a free open-source library for building AI-powered applications and agents

Test your prompts, agents, and RAGs. Red teaming/pentesting/vulnerability scanning for AI. Compare performance of GPT, Claude, Gemini, DeepSeek, and more. Simple declarative configs with command line and CI/CD integration. Used by OpenAI and Anthropic.

Context window optimization for AI coding agents. Sandboxes tool output (98% reduction), persists session memory, and enforces routing across 17 platforms via MCP + hooks.

A collection of projects designed to help developers quickly get started with building deployable applications using the Claude API

OpenWiki is a CLI that writes and maintains agent documentation for your codebase.

AG-UI: the Agent-User Interaction Protocol. Bring Agents into Frontend Applications.

Multiplayer agent harness for work.

The best agent harness.

Practical patterns, starters & CLI tools for loop engineering with AI coding agents. Design systems that prompt and orchestrate agents (inspired by Addy Osmani and Boris Cherny). Includes loop-audit, loop-init, loop-cost.

Free, local tool to track AI coding token usage and cost across 37 tools and agents (Claude Code, Cursor, Codex, Gemini and more), by model, project, and task. npx codeburn

Visual testing tool for MCP servers

The sandbox agent framework.

Deepsec is a security harness for finding vulnerabilities in your codebase powered by coding agents

Orchestrate sandboxed coding agents in TypeScript with sandcastle.run()

Kimi Code CLI — The Starting Point for Next-Gen Agents

Self-hosted TypeScript agent runtime with durable approvals and verifiable run records. Own it, approve it, audit it.

Self-hosted control plane for AI agents: dispatch tasks, review runs, track spend, and operate OpenClaw, Claude Code, Codex, and other runtimes.

🧊 Open source LLM observability platform. One line of code to monitor, evaluate, and experiment. YC W23 🍓

Open-source auth gateway connecting 1400+ SaaS providers to AI agents through SDK, CLI, MCP, HTTP, and OpenAPI.

The open-source agent harness - the runtime layer that turns an LLM into a working agent.

TencentDB Agent Memory delivers fully local long-term memory for AI Agents via a 4-tier progressive pipeline, with zero external API dependencies.

The missing DevTools for Claude Code — inspect session logs, tool calls, token usage, subagents, and context window in a visual UI. Free, open source.

The World's First Virtual Terminal for AI Agents

Squad: AI agent teams for any project

Skills, MCP servers, Custom Agents, Agents.md for SDKs to ground Coding Agents

Coding Agent singularly focused efficiency and context curation. Reduces API costs by 50-80% vs other agent AND improves the code quality at the same time. Uses Hash Anchored edits, massively parallel operations, AST manipulation and many many other optimizations. https://dirac.run/

React components for visualizing traces from AI agents

tui-use lets agents interact with programs that expect a human at the keyboard — REPLs, debuggers, TUI apps, and anything else bash can't reach.

MCP Fusion - The TypeScript framework for secure MCP servers.

Open HTTP protocol for human decisions in AI agent workflows. Service-hosted reviews, structured approvals, selections and forms, with optional messenger actions.