OpenSpec

OpenSpec is a lightweight, open-source, spec-driven framework that works universally across AI coding agents without requiring API keys or MCP. It stores functional requirements as markdown specs directly in your repository, giving agents persistent context that survives across chat sessions and team changes. By generating spec deltas alongside code changes, OpenSpec enables developers and reviewers to understand intent, not just implementation.

• Spec-driven planning — Install via npm install -g @fission-ai/openspec@latest and initialize specs in your repo to start capturing functional requirements per capability.
• Spec deltas on every change — Each proposed change generates a diff of requirements, making it easy to review what the system is supposed to do before any code is written.
• Persistent context — Specs live in your codebase alongside code, organized by capability, so context never disappears when a chat session ends or a team member leaves.
• Proposal generation — Use slash commands like /openspec:proposal to generate a full proposal document, technical design decisions, implementation tasks, and spec deltas in seconds.
• Brownfield-first — Designed for mature codebases where understanding existing behavior is the real challenge, not just greenfield projects.
• Universal agent support — Natively integrates with Claude Code, Cursor, Codex, GitHub Copilot, Windsurf, Gemini CLI, Cline, RooCode, Amazon Q, and 20+ more coding agents.
• No vendor lock-in — No API keys, no MCP dependency; specs are plain markdown files checked into your repo and portable across any agent.
• Team collaboration via Git — Specs and change proposals are version-controlled, enabling PR-based reviews and standard Git workflows for collaboration.
• Coming soon: Workspaces — Team-focused features for large codebases, multi-repo planning, customization, and deeper integrations are in active development.