Openspec

OpenSpec (by Fission-AI) is an open-source, lightweight spec-driven development (SDD) framework for AI coding assistants. It adds a durable spec layer so you and your coding agent agree on what to build before any code is written: each change gets its own folder with a proposal, specs, design, and tasks, following a propose - apply - archive workflow. OpenSpec is a CLI and agent contract (installed via npm, no API keys or MCP required) that works with 30+ AI tools including Claude Code, Cursor, Windsurf, and Copilot via slash commands. A Y Combinator company, OpenSpec has 60k+ GitHub stars and is building Workspaces for teams needing multi-repo planning and collaboration.

Openspec is profiled on the APIs.io network. Tagged areas include Spec-Driven Development, AI Coding Assistants, Developer Tools, CLI, and Specifications.

Openspec’s developer surface includes documentation, getting-started guide, API reference, changelog, support, CLI, and 10 more developer resources.

🌐 Visit website 📡 Source on GitHub

16.2/100 emerging ▬ flat Agent 0/100 human only Full breakdown ↓
scored 2026-08-20 · rubric v0.12.0

AccessOpen

0 APIs

Spec-Driven DevelopmentAI Coding AssistantsDeveloper Tools CLI Specifications Context Engineering Open-Source Coding Agents

Kin Score

Kin Score How this is scored →
scored 2026-08-20 · rubric v0.12.0

Composite quality — 16.2/100 · emerging

Contract Quality 0.0 / 25

Developer Ergonomics 8.1 / 20

Access Clarity 0.0 / 20

Operational Transparency 2.4 / 13

Contract Governance 0.0 / 12

Discoverability 5.7 / 10

Agent readiness — 0/100 · human only

Machine-Readable Contract 0 / 18

Agentic Access Contract 0 / 10

Documented Reversibility 0 / 6

MCP Server 0 / 12

Machine-Readable Auth 0 / 10

Idempotency 0 / 9

Stable Error Semantics 0 / 8

Request/Response Examples 0 / 7

Rate-Limit Signaling 0 / 7

Typed Event Surface 0 / 6

Agent Skills 0 / 5

Well-Known Catalog 0 / 4

Consent & Bot Identity 0 / 3

A2A Agent Card 0 / 8

Dry-Run / Simulate Mode 0 / 4

Improve this rating by publishing the missing artifacts — every area above can be raised, and the full rubric is at apis.io/rating/. This rating is computed from github.com/api-evangelist/openspec: open an issue to ask a question, or submit a pull request to add artifacts. Want it done for you? Prioritized profiling — $2,500 →

Get Started 2

Portal, sign-up, and the first successful call

DeveloperPortal

DeveloperPortal

GettingStarted

GettingStarted

Documentation 2

Reference material describing how the API behaves

Documentation

Documentation

APIReference

APIReference

Agent Surfaces 1

MCP servers, agent skills, and machine-readable catalogs

LLMsTxt

LLMsTxt

Build 4

SDKs, sample code, and the tooling you integrate with

SourceCode

SourceCode

GitHubOrganization

GitHubOrganization

Packages

Packages

CLI

CLI

Access & Security 1

Authentication, authorization, and security posture

DomainSecurity

DomainSecurity

Operate 4

Status, limits, changes, and where to get help

ChangeLog

Support

Community

ChangeLog

Commercial 1

Pricing, plans, and the legal terms of use

License

License

Company 1

The organization behind the API

Website

Website

Source (apis.yml)

aid: openspec
name: Openspec
description: 'OpenSpec (by Fission-AI) is an open-source, lightweight spec-driven development (SDD) framework for AI coding
  assistants. It adds a durable spec layer so you and your coding agent agree on what to build before any code is written:
  each change gets its own folder with a proposal, specs, design, and tasks, following a propose - apply - archive workflow.
  OpenSpec is a CLI and agent contract (installed via npm, no API keys or MCP required) that works with 30+ AI tools including
  Claude Code, Cursor, Windsurf, and Copilot via slash commands. A Y Combinator company, OpenSpec has 60k+ GitHub stars and
  is building Workspaces for teams needing multi-repo planning and collaboration.'
url: https://raw.githubusercontent.com/api-evangelist/openspec/refs/heads/main/apis.yml
accessModel:
  pricing: unknown
  onboarding: open
  trial: false
  try_now: false
  public: true
  label: Open access
  confidence: medium
  source: []
  generated: '2026-07-22'
  method: derived
image: https://avatars.githubusercontent.com/u/203414896?v=4
x-type: company
x-source: vc-portfolio
x-backed-by:
- y-combinator
x-tier: stub
x-tier-reason: portfolio-lead
specificationVersion: '0.23'
created: '2026-07-17'
modified: '2026-07-20'
tags:
- Spec-Driven Development
- AI Coding Assistants
- Developer Tools
- CLI
- Specifications
- Context Engineering
- Open-Source
- Coding Agents
tags_raw:
- Spec-Driven Development
- AI Coding Assistants
- Developer Tools
- CLI
- Specifications
- Context Engineering
- Open Source
- Coding Agents
apis: []
x-enrichment:
  date: '2026-07-20'
  status: enriched
  artifacts_added: 5
  pass: local-v1
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com
- FN: APIs.json
  email: info@apis.io
common:
- type: License
  name: MIT
  url: https://github.com/Fission-AI/OpenSpec/blob/main/LICENSE
- type: Website
  url: https://openspec.dev
- type: DeveloperPortal
  url: https://openspec.dev
- type: Documentation
  url: https://openspec.dev/docs
- type: GettingStarted
  url: https://openspec.dev/docs/getting-started
- type: APIReference
  url: https://openspec.dev/docs/reference/cli
- type: SourceCode
  url: https://github.com/Fission-AI/OpenSpec
- type: GitHubOrganization
  url: https://github.com/Fission-AI
- type: ChangeLog
  url: https://github.com/Fission-AI/OpenSpec/blob/main/CHANGELOG.md
- type: Support
  url: https://openspec.dev/docs/troubleshooting
- type: Community
  url: https://discord.gg/YctCnvvshC
- type: Packages
  url: packages/openspec-packages.yml
- type: CLI
  url: cli/openspec-cli.yml
- type: LLMsTxt
  url: llms/openspec-llms.txt
- type: ChangeLog
  url: changelog/openspec-changelog.yml
- type: DomainSecurity
  url: security/openspec-domain-security.yml