Frequently Asked Questions

OpenSpec is a lightweight, open-source spec-driven development (SDD) framework designed to help AI coding assistants follow instructions more effectively. It allows developers and AI to agree on specifications before code is written, ensuring predictable and organized development workflows.

No, the core OpenSpec CLI requires no API keys or MCP (Model Context Protocol) integration. It's completely free and works by organizing specifications in your repository alongside your code.

Optional MCP Server: There is an optional MCP server implementation (openspec-mcp) that provides MCP integration for universal AI assistant support, including a web dashboard and approval workflow. This is optional and not required for basic OpenSpec usage.

The OpenSpec MCP Server is an optional implementation that provides Model Context Protocol (MCP) integration for OpenSpec. It enables any MCP-compatible AI assistant (Claude, GitHub Copilot, Amazon Q, etc.) to directly interact with OpenSpec's change proposals, specifications, and project context.

Features include:

• MCP server for universal AI assistant integration
• Web dashboard for visual change management
• Approval workflow system
• Kanban board for task tracking
• QA dashboard and project context analysis

Learn more: OpenSpec MCP Integration Guide

OpenSpec works with 20+ AI coding assistants including:

• Cursor
• Claude Code
• GitHub Copilot
• Windsurf
• RooCode
• Cline
• Amazon Q Developer
• And many more

See the complete list of supported tools.

Install OpenSpec globally using npm:

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

Then navigate to your project directory and run:

openspec init

See our getting started guide for detailed instructions.

The main OpenSpec slash commands are:

• /opsx:new <feature-name> - Create a new change proposal
• /opsx:ff - Fast-forward: generate all planning documents
• /opsx:apply - Implement all tasks from the current change
• /opsx:archive - Archive completed changes and update specs

OpenSpec requires Node.js 20.19.0 or higher. You can check your version with:

node --version

Yes! OpenSpec creates an AGENTS.md file that contains instructions for your AI assistant. Tools that can read markdown files can use OpenSpec workflows. You can also describe OpenSpec commands in natural language to your AI assistant.

vs. Spec Kit: OpenSpec is lighter and more flexible. Spec Kit is thorough but heavyweight with rigid phase gates and requires Python setup. OpenSpec lets you iterate freely without Python. Setup takes 5 minutes vs 30 minutes. OpenSpec generates ~250 lines of specs vs Spec Kit's ~800 lines, making review faster.

vs. BMAD: BMAD is a powerful multi-agent system but requires hours or days to set up and has a steep learning curve. OpenSpec focuses on spec management with a 5-minute setup. BMAD is better for enterprise-scale projects with multi-repo complexity, while OpenSpec excels at change-centric workflows.

vs. Kiro: Kiro is powerful but locked into their IDE and limited to Claude models. OpenSpec works with the tools you already use with no vendor lock-in. Kiro requires an AWS account, while OpenSpec works anywhere.

See our detailed comparison page for a complete analysis.

Brownfield projects are existing codebases with legacy code, established patterns, and ongoing maintenance. Most real-world development happens in brownfield projects.

Greenfield projects are new projects started from scratch with no existing codebase.

OpenSpec is built for brownfield: It's designed to work with existing codebases, allowing you to add spec-driven development to any project without disrupting current workflows. You can initialize OpenSpec in an existing project and start using it immediately.

Spec Kit is optimized for greenfield: It works best when starting new projects from scratch, where you can establish the full spec-driven workflow from day one.

This is one of OpenSpec's key differentiators - it's the only tool purpose-built for existing codebases.

OpenSpec creates an openspec/ directory with:

• changes/ - Active change proposals
• archive/ - Completed changes

Each change includes:

• proposal.md - Why and what's changing
• specs/ - Requirements and scenarios
• design.md - Technical approach
• tasks.md - Implementation checklist

Absolutely! OpenSpec is built for brownfield projects, not just greenfield. You can initialize OpenSpec in any existing project and start using it immediately. It won't interfere with your existing code structure.

OpenSpec works best with high-reasoning models. We recommend:

• Opus 4.5
• GPT 5.2
• Other high-reasoning models

These models excel at both planning and implementation phases.

To update OpenSpec, run:

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

Then refresh agent instructions in your project:

openspec update

OpenSpec collects anonymous usage statistics (command names and version only). No arguments, paths, content, or PII is collected. Telemetry is automatically disabled in CI environments.

To opt-out, set:

export OPENSPEC_TELEMETRY=0

Or:

export DO_NOT_TRACK=1

• Discord community - Join for help and questions
• GitHub Issues - Report bugs or request features
• GitHub Repository - Full documentation
• Follow @0xTab - Updates and announcements

Yes, OpenSpec is completely free and open-source under the MIT License. There are no paid plans, no API keys required, and no usage limits.