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 9 more developer resources.

🌐 Visit website 📡 Source on GitHub
18.6/100 emerging ▬ flat Agent 0/100 human only Full breakdown ↓
scored 2026-07-28 · rubric v0.5
AccessOpen
0 APIs
Spec-Driven DevelopmentAI Coding AssistantsDeveloper ToolsCLISpecificationsContext EngineeringOpen SourceCoding Agents

Kin Score

Kin Score Kin Score How this is scored →
scored 2026-07-28 · rubric v0.5
Composite quality — 18.6/100 · emerging
Contract Quality 0.0 / 25
Developer Ergonomics 9.1 / 20
Commercial Clarity 0.0 / 20
Operational Transparency 2.7 / 13
Governance 0.0 / 12
Discoverability 6.8 / 10
Agent readiness — 0/100 · human only
Machine-Readable Contract 0 / 18
Agentic Access Contract 0 / 15
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
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 →

Security Posture 1

Authentication, domain security, vulnerability disclosure, and trust-center signals.

Openspec Domain Security

TLSv1.3

SECURITY

Resources

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
ChangeLog
 Support
Support
 Community
Community
 ChangeLog
ChangeLog

Company 1

The organization behind the API

Website
Website

Source (apis.yml)

apis.yml Raw ↑ 
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: '0.20'
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
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: 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