RefOpenSpec - A Lightweight Spec-Driven Framework

OpenSpec - A Lightweight Spec-Driven Framework

OpenSpec - A Lightweight Spec-Driven Framework

Universal planning layer for AI coding agents. Review intent, not just code.

OpenSpec Screenshot

What Is It?

OpenSpec is a lightweight, spec-driven framework that acts as a planning layer for AI coding agents. It's:

  • Universal - works across 20+ coding tools
  • Open Source - no API keys required
  • No MCP - direct integration

What Problem Does It Solve?

1. Review Intent, Not Just Code

Each OpenSpec change produces a spec delta that captures the change in requirements. This makes it easy for:

  • Developers to understand how they're modifying the system
  • Reviewers to understand changes without digging through code
  • Teams to gain high-level understanding quickly

2. Universal Planning Format

Specs live in your codebase and work with any agent:

  • Claude Code
  • Cursor
  • Codex
  • GitHub Copilot
  • 16+ more tools

3. Better Than Prompts

Specs provide persistent, reviewable requirements instead of one-off prompts that get lost.

How to Use It Quickly

# Install globally
npm install -g @fission-ai/openspec@latest

# Initialize in your project
openspec init

# Start planning
openspec plan

Specs live in your codebase (e.g., openspec/specs/auth-session/spec.md) and generate diffs like:

### Requirement: Session expiration
- The system SHALL expire sessions after a configured duration.
+ The system SHALL support configurable session expiration periods.

#### Scenario: Default session timeout
- GIVEN a user has authenticated
- - WHEN 24 hours pass without activity
+ - WHEN 24 hours pass without "Remember me"
- THEN invalidate the session token

+ #### Scenario: Extended session with remember me
+ - GIVEN user checks "Remember me" at login
+ - WHEN 30 days have passed
+ - THEN invalidate the session token
+ - AND clear the persistent cookie

Key Features

  • Native Support for 20+ coding agents
  • Spec Deltas - see requirement changes, not just code changes
  • Version Controlled - specs live in your repo
  • Team Ready - workspaces coming soon for multi-repo planning

Coming Soon: Workspaces

OpenSpec is building team features for:

  • Large codebases
  • Multi-repo planning
  • Custom integrations
  • Better collaboration

By

Fission AI

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