OpenSpec
A local, open-source planning tool helps AI coding assistants work from Markdown requirements, design notes and tasks, with support for Codex and Cursor.
OpenSpec helps developers agree on what an AI coding assistant should build before it edits code. It keeps requirements and implementation plans in project files so they don't depend on chat history, and supports both existing codebases and new projects.
- Reviewable requirements: Your assistant drafts Markdown requirements with concrete scenarios that you can review before implementation.
- Plans for each change: Keep the proposal, specifications, technical design and task checklist together for each feature or fix.
- Exploration and revision: Ask your assistant to examine the code and weigh approaches before committing to a plan, then revise planning documents as the work develops without fixed phase gates.
- Implementation and archiving: Guide the assistant through planned tasks, then archive completed changes and update the project's specifications.
- Assistant integrations: Use the workflow with Codex, Claude Code, Cursor, GitHub Copilot or Amazon Q rather than adopting a separate editor.
OpenSpec is an open-source local command-line tool under the MIT license. It requires Node.js, and Homebrew distribution supports macOS and Linux. Planning files live in your project; AI work uses the coding assistant you pair it with. Anonymous telemetry is enabled by default and reports command names and the tool version, excluding arguments, paths and content. You can disable it.
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