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OpenSpec

Plan each change with your AI coding assistant as proposal, spec, design and task files before any code is written.

Repository owner Fission-AI

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Published 11 Oct 2026Listing updated 12 Oct 2026

At a glance

Purpose: Plan each change with your AI coding assistant as proposal, spec, design and task files before any code is written.
Runs in: Local agent with shell
Operating systems: macOS, Linux
Needs: Runtime: Node.js 20.19.0+; Needs internet: Yes; Needs accounts or API keys beyond your agent: Not stated
Files and data: Reads files: Yes; Writes files: Yes; Sends data to other services: Yes
Tool type: Skill
Delivery: From GitHub
Version: Latest on the main branch
Access: Code on GitHub
Compatibility: According to the README, OpenSpec supports 30+ AI tools, including Cursor, GitHub Copilot, Amazon Q and Codex, and openspec init prints the right command form for the tools you pick. It installs with npm, Homebrew, pnpm, yarn, bun or Nix.
External costs: The repository is MIT-licensed and states no pricing. Your coding assistant or model provider may charge for usage.
Permissions: The tool acts through your coding assistant with the access you give it. According to the README, you install OpenSpec as a global command-line package (npm install -g, or Homebrew), openspec init sets up OpenSpec in your project and prints the command form for your tools, openspec update regenerates agent guidance and slash commands, and changes are stored as Markdown files in an openspec folder in your repository. The README also offers a setup prompt you can paste into your coding assistant so that it installs the CLI and runs openspec init, and says OpenSpec collects anonymous usage statistics unless you opt out. The README also mentions an optional Stores feature (beta) that shares planning through a separate repository using git push.
Usage terms: MIT License, as stated in the repository. See its LICENSE file for the exact terms.

Code on GitHub

Fission-AI/OpenSpec

MIT

TypeScript71,753 stars4,897 forksLast pushed 12 Oct 2026 UTC

Spec-driven development (SDD) for AI coding assistants.

Topics: ai context-engineering engineering planning prd sdd sdlc spec

Public GitHub data fetched 13 Oct 2026 UTC · 0 days old

Skill folders in this repository (16)

Folders that contain a SKILL.md file, from GitHub's file list on 13 Oct 2026 UTC.

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What it does

OpenSpec is a spec-driven development tool for AI coding assistants. According to the README, it adds a lightweight spec layer so that you and your assistant agree on what to build before any code is written. You install a command-line tool, then work through slash commands in your assistant.

The README describes a flow of /opsx:explore, /opsx:propose, /opsx:apply and /opsx:archive. A proposal creates a change folder under openspec/changes with proposal, specs, design and task files, and archiving updates the specs. The specs are plain Markdown requirements with scenarios. An expanded profile adds /opsx:new, /opsx:continue, /opsx:ff, /opsx:verify, /opsx:bulk-archive and /opsx:onboard.

The README also describes Stores, a beta feature that keeps planning in a repository of its own so several code repositories can share specs. The repository's skills cover exploring, proposing, applying, archiving, syncing and updating changes.

Who it is for

Developers and teams who use AI coding assistants and want requirements agreed in writing before the assistant writes code.

Example tasks

Initialize OpenSpec in a project with openspec init.
Explore an idea with /opsx:explore before committing to a plan.
Create a change proposal with /opsx:propose add-dark-mode.
Implement the tasks in a proposal with /opsx:apply.
Archive a finished change with /opsx:archive so the specs update.

Getting started

According to the README, install the package with npm install -g @fission-ai/openspec@latest, or on macOS or Linux with brew install openspec. Then change into your project directory, run openspec init, and talk to your AI with /opsx:explore or /opsx:propose <what-you-want-to-build>. Run openspec update inside each project to refresh agent instructions after upgrading. The README has the exact commands.

Limitations

OpenSpec requires Node.js 20.19.0 or higher, according to the README, and an AI coding assistant from its list of 30+ supported tools. The README says it works best with high-reasoning models, recommends Codex 5.5 and Opus 4.7 for planning and implementation, and benefits from a clean context window. The README says the slash command form differs by tool, for example /opsx-propose in Cursor and GitHub Copilot, @opsx-propose in Amazon Q and $openspec-propose in Codex. Stores are in beta. The README says /opsx:explore and /opsx:propose are in the default profile, and the expanded workflow is selected with openspec config profile and applied with openspec update. The repository can change at any time; check its README before you install.

Data practices

According to the README, OpenSpec collects anonymous usage statistics: only command names and version, with no arguments, paths, content or personal information, and collection is automatically disabled in CI. You can opt out with openspec config set telemetry.enabled false, or by setting OPENSPEC_TELEMETRY=0 or DO_NOT_TRACK=1. The README does not say where the statistics are sent. What your assistant and model provider receive depends on them.