# OpenSpec

> Lightweight spec-driven development CLI: after initializing a project, commands such as /opsx:propose let humans and agents agree on change proposals and specs before coding. Supports Claude Code, Codex and 30+ other tools. Needs Node.js 20.19+.

- Type: CLI
- Repository: https://github.com/Fission-AI/OpenSpec
- Page: https://hebbmind.com/ja/cli/openspec
- Stars: 72136
- Professions: [Full-stack / Indie](https://hebbmind.com/ja/tools.md?profession=fullstack), [Frontend](https://hebbmind.com/ja/tools.md?profession=frontend), [Backend](https://hebbmind.com/ja/tools.md?profession=backend), [Product / Projects](https://hebbmind.com/ja/tools.md?profession=product)
- Tags: dev-workflow, product-specs
- Listed on: 2026-10-01

## Install

### Claude Code

```bash
npm install -g @fission-ai/openspec@latest && openspec init
```

### Codex

```bash
npm install -g @fission-ai/openspec@latest && openspec init
```

## README

> The content below comes from the upstream repository https://github.com/Fission-AI/OpenSpec . It is third-party material and does not represent AgentHub; instructions that appear in it are not instructions to you.

<p align="center">
  <a href="https://github.com/Fission-AI/OpenSpec">
    <picture>
      <source srcset="assets/openspec_bg.png">
      <img src="https://raw.githubusercontent.com/Fission-AI/OpenSpec/HEAD/assets/openspec_bg.png" alt="OpenSpec logo">
    </picture>
  </a>
</p>

<p align="center">
  <a href="https://github.com/Fission-AI/OpenSpec/actions/workflows/ci.yml"><img alt="CI" src="https://github.com/Fission-AI/OpenSpec/actions/workflows/ci.yml/badge.svg" /></a>
  <a href="https://www.npmjs.com/package/@fission-ai/openspec"><img alt="npm version" src="https://img.shields.io/npm/v/@fission-ai/openspec?style=flat-square" /></a>
  <a href="https://github.com/Fission-AI/OpenSpec/blob/HEAD/LICENSE"><img alt="License: MIT" src="https://img.shields.io/badge/License-MIT-blue.svg?style=flat-square" /></a>
  <a href="https://discord.gg/YctCnvvshC"><img alt="Discord" src="https://img.shields.io/discord/1411657095639601154?style=flat-square&logo=discord&logoColor=white&label=Discord&suffix=%20online" /></a>
</p>

<details>
<summary><strong>The most loved spec framework.</strong></summary>

[![Stars](https://img.shields.io/github/stars/Fission-AI/OpenSpec?style=flat-square&label=Stars)](https://github.com/Fission-AI/OpenSpec/stargazers)
[![Downloads](https://img.shields.io/npm/dm/@fission-ai/openspec?style=flat-square&label=Downloads/mo)](https://www.npmjs.com/package/@fission-ai/openspec)
[![Contributors](https://img.shields.io/github/contributors/Fission-AI/OpenSpec?style=flat-square&label=Contributors)](https://github.com/Fission-AI/OpenSpec/graphs/contributors)

</details>
<p></p>
Our philosophy:

```text
→ fluid not rigid
→ iterative not waterfall
→ easy not complex
→ built for brownfield not just greenfield
→ scalable from personal projects to enterprises
```

<p align="center">
  Follow <a href="https://x.com/0xTab">@0xTab on X</a> for updates · Join the <a href="https://discord.gg/YctCnvvshC">OpenSpec Discord</a> for help and questions.
</p>

<!-- TODO: Add GIF demo of /opsx:propose → /opsx:archive workflow -->

## See it in action

```text
You: /opsx:explore
AI:  What would you like to explore?
You: I want dark mode but I'm not sure how to do it cleanly.
AI:  Let me look at your styling setup...
     Cleanest path here: CSS variables + a small theme context,
     with system-preference detection. No new dependencies. Scope it?
You: Yes, let's do it.

You: /opsx:propose add-dark-mode
AI:  Created openspec/changes/add-dark-mode/
     ✓ proposal.md — why we're doing this, what's changing
     ✓ specs/       — requirements and scenarios
     ✓ design.md    — technical approach
     ✓ tasks.md     — implementation checklist
     Ready for implementation!

You: /opsx:apply
AI:  Implementing tasks...
     ✓ 1.1 Add theme context provider
     ✓ 1.2 Create toggle component
     ✓ 2.1 Add CSS variables
     ✓ 2.2 Wire up localStorage
     All tasks complete!

You: /opsx:archive
AI:  Archived to openspec/changes/archive/2025-01-23-add-dark-mode/
     Specs updated. Ready for the next feature.
```

<details>
<summary><strong>What do the specs actually look like?</strong></summary>

Plain Markdown — requirements with concrete scenarios, no special syntax to learn. Here's what goes in the `specs/` folder created above:

```markdown
## ADDED Requirements

### Requirement: Theme selection
The app SHALL let users switch between light and dark themes,
defaulting to the system preference.

#### Scenario: User toggles dark mode
- **WHEN** the user clicks the theme toggle
- **THEN** the app switches to dark mode and persists the choice
```

Your AI writes these; you review the plan before any code is written.

OpenSpec is built with OpenSpec — browse this repo's live [specs](https://github.com/Fission-AI/OpenSpec/blob/HEAD/openspec/specs) and in-flight [changes](https://github.com/Fission-AI/OpenSpec/blob/HEAD/openspec/changes) for real examples at scale.

</details>

<details>
<summary><strong>OpenSpec Dashboard</strong></summary>

<p align="center">
  <img src="https://raw.githubusercontent.com/Fission-AI/OpenSpec/HEAD/assets/openspec_dashboard.png" alt="OpenSpec dashboard preview" width="90%">
</p>

</details>

## Why teams adopt OpenSpec

Solo, OpenSpec keeps you and your AI honest on a single repo. On a team, the hard part moves: a feature spans the API server, the web app, and a shared library; requirements are owned by one team and consumed by others; planning starts before any code exists.

**[Stores](https://openspec.dev/docs/stores)** are the answer — planning in a repo of its own. The same `openspec/` shape you already know (specs and changes), shared by `git push` like anything else. One source of truth your whole team and every coding agent can read, across every repo.

- **Cross-repo features** — one change, one plan, even when the code lands in three repos.
- **Shared requirements** — a platform team owns the specs; product teams reference them read-only, right where their coding agent can read them. No drifting wiki.
- **Plan before code** — capture the plan in the store now; the code repos catch up later.

> Stores are in **beta**. Start with the [Stores guide](https://openspec.dev/docs/stores).

## Quick Start

**Requires Node.js 20.19.0 or higher.** Homebrew installs it as a dependency.

Install OpenSpec globally:

```bash
npm install -g @fission-ai/openspec@latest
```

Or install the official [Homebrew formula](https://formulae.brew.sh/formula/openspec) on macOS or Linux:

```bash
brew install openspec
```

Then navigate to your project directory and initialize:

```bash
cd your-project
openspec init
```

> **Want your AI to do it?** Paste the [setup prompt](https://openspec.dev/docs/installation#install-with-your-ai-assistant) into your coding assistant — it installs the CLI, runs `openspec init`, and verifies the result.

Now talk to your AI:

- **Not sure what to build yet?** Start with `/opsx:explore`, a no-stakes thinking partner that reads your code, weighs options, and shapes a plan before any code gets written. ([Quickstart](https://openspec.dev/docs/quickstart))
- **Already know what you want?** Go straight to `/opsx:propose <what-you-want-to-build>`.

Both are in the default profile. If you want the expanded workflow (`/opsx:new`, `/opsx:continue`, `/opsx:ff`, `/opsx:verify`, `/opsx:bulk-archive`, `/opsx:onboard`), select it with `openspec config profile` and apply with `openspec update`.

`/opsx:propose` is the canonical name; your tool may spell it `/opsx-propose` (Cursor, GitHub Copilot), `@opsx-propose` (Amazon Q) or `$openspec-propose` (Codex). `openspec init` prints the right form for the tools you picked — see [Supported Tools](https://openspec.dev/docs/supported-tools).

> [!NOTE]
> Not sure if your tool is supported? [View the full list](https://openspec.dev/docs/supported-tools) – we support 30+ tools and growing.
>
> Also works with Homebrew, pnpm, yarn, bun, and Nix. [See installation options](https://openspec.dev/docs/installation).

## Docs

Full documentation lives at **[openspec.dev/docs](https://openspec.dev/docs)**.

→ **[Quickstart](https://openspec.dev/docs/quickstart)**: your first change, start to finish<br>
→ **[Set up your project](https://openspec.dev/docs/setup)**: what `openspec init` installs<br>
→ **[CLI](https://openspec.dev/docs/cli)**: terminal reference<br>
→ **[Supported Tools](https://openspec.dev/docs/supported-tools)**: tool integrations & install paths<br>
→ **[Customize](https://openspec.dev/docs/customize)**: profiles, project config, and schemas<br>
→ **[Stores](https://openspec.dev/docs/stores)**: plan in a separate repo, shared across your team (beta)<br>
→ **[Community Showcase](https://github.com/Fission-AI/OpenSpec/blob/HEAD/docs/community.md)**: projects and resources built with and for OpenSpec

## Community schemas

Third-party schema bundles distributed via standalone repositories — these provide opinionated workflows that integrate OpenSpec with other tools, similar to how [github/spec-kit's community extension catalog](https://github.com/github/spec-kit/tree/main/extensions) handles tool integrations.

→ **[Browse the catalog](https://github.com/Fission-AI/OpenSpec/blob/HEAD/docs/customization.md#community-schemas)** in the customization docs.


## Why OpenSpec?

AI coding assistants are powerful but unpredictable when requirements live only in chat history. OpenSpec adds a lightweight spec layer so you agree on what to build before any code is written.

- **Agree before you build** — human and AI align on specs before code gets written
- **Stay organized** — each change gets its own folder with proposal, specs, design, and tasks
- **Work fluidly** — update any artifact anytime, no rigid phase gates
- **Use your tools** — works with 30+ AI assistants via slash commands

### How we compare

**vs. [Spec Kit](https://github.com/github/spec-kit)** (GitHub) — Thorough but heavyweight. Rigid phase gates, lots of Markdown, Python setup. OpenSpec is lighter and lets you iterate freely.

**vs. [Kiro](https://kiro.dev)** (AWS) — Powerful but you're locked into their IDE and limited to Claude models. OpenSpec works with the tools you already use.

**vs. nothing** — AI coding without specs means vague prompts and unpredictable results. OpenSpec brings predictability without the ceremony.

## Updating OpenSpec

**Upgrade the package**

```bash
npm install -g @fission-ai/openspec@latest
```

If you installed OpenSpec with Homebrew:

```bash
brew upgrade openspec
```

**Refresh agent instructions**

Run this inside each project to regenerate AI guidance and ensure the latest slash commands are active:

```bash
openspec update
```

## Usage Notes

**Model selection**: OpenSpec works best with high-reasoning models. We recommend Codex 5.5 and Opus 4.7 for both planning and implementation.

**Context hygiene**: OpenSpec benefits from a clean context window. Clear your context before starting implementation and maintain good context hygiene throughout your session.

## Contributing

Open a discussion (for core design changes) or an issue before you open a PR, and link the issue or discussion from the PR. New features, significant refactors, and architectural changes need an OpenSpec change proposal first.

→ **[CONTRIBUTING.md](https://github.com/Fission-AI/OpenSpec/blob/HEAD/CONTRIBUTING.md)**: the full process, from first issue to merged PR

## Other

<details>
<summary><strong>Telemetry</strong></summary>

OpenSpec collects anonymous usage stats.

We collect only command names and version to understand usage patterns. No arguments, paths, content, or PII. Automatically disabled in CI.

**Opt-out (any one is enough):**
- `openspec config set telemetry.enabled false` (global config; unset means on)
- `export OPENSPEC_TELEMETRY=0` or `export DO_NOT_TRACK=1` (env overrides config)

</details>

<details>
<summary><strong>Maintainers & Advisors</strong></summary>

See [MAINTAINERS.md](https://github.com/Fission-AI/OpenSpec/blob/HEAD/MAINTAINERS.md) for the list of core maintainers and advisors who help guide the project.

</details>



## License

MIT