Installation

Prerequisites

• Node.js 20.19.0 or higher — Check your version: node --version

Package Managers

npm

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

pnpm

pnpm add -g @fission-ai/openspec@latest

yarn

yarn global add @fission-ai/openspec@latest

bun

Bun can install OpenSpec globally, but OpenSpec currently runs on Node.js. You still need Node.js 20.19.0 or higher available on PATH.

bun add -g @fission-ai/openspec@latest

Nix

Run OpenSpec directly without installation:

nix run github:Fission-AI/OpenSpec -- init

Or install to your profile:

nix profile install github:Fission-AI/OpenSpec

Or add to your development environment in flake.nix:

{
  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
    openspec.url = "github:Fission-AI/OpenSpec";
  };

  outputs = { nixpkgs, openspec, ... }: {
    devShells.x86_64-linux.default = nixpkgs.legacyPackages.x86_64-linux.mkShell {
      buildInputs = [ openspec.packages.x86_64-linux.default ];
    };
  };
}

Verify Installation

openspec --version

Next Steps

After installing, initialize OpenSpec in your project:

cd your-project
openspec init

See Getting Started for a full walkthrough.