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OpenCap Stack

OpenCap Stack is an open-source cap table and equity management platform built for startups, growth-stage companies, and the AI agents that work with them. Every feature is available via a REST API and MCP server — so you can manage equity from code, from Claude, or from any MCP-compatible agent.

API Basehttps://api.opencapstack.com/api/v1
MCP Package@opencapstack/mcp-server@1.6.0
Schema StandardOCTA v2.0 (Open Cap Table Alliance)
LicenseMIT — self-host for free
Docshttps://opencapstack.com/developers
GitHubhttps://github.com/Open-Cap-Stack/opencapstack

What You Can Build​

  • Cap table dashboards — query live ownership data, dilution models, vesting schedules
  • AI-powered equity agents — let Claude manage grants, approve SAFEs, run waterfall analysis
  • Investor portals — pull stakeholder data, generate reports, export to OCTA format
  • 409A automation — trigger valuations, retrieve results, integrate with finance workflows
  • Onboarding automation — provision stakeholders, issue grants, send notifications programmatically

Core Concepts​

ConceptDescription
StakeholderAny person or entity with equity — founder, investor, employee, advisor
ShareClassCommon, preferred (Series A/B/C), options pool
EquityGrantStock options, RSUs, warrants with vesting schedules
SAFENoteSimple Agreement for Future Equity with valuation cap and discount rate
Valuation409AIRS-compliant fair market value determination
FundraisingRoundRound details, investors, dilution modeling
DocumentLegal docs, grant agreements, board consents

Architecture​

Your App / AI Agent
        │
        ├── REST API  ──►  https://api.opencapstack.com/api/v1
        │                           │
        └── MCP Server ─────────────┘
             (via Claude Code,               ZeroDB (primary DB)
              Cursor, Windsurf)              MinIO (document storage)
                                            AINative Auth (SSO)

Guides in This Section​

GuideWhat it covers
AuthenticationAINative SSO, email/password, API keys, agent tokens
REST APIFull endpoint reference with examples
MCP Server29 tools, setup for Claude Code / Cursor / Windsurf
Builders GuideEnd-to-end: build a cap table agent from scratch
OCTA SchemaData model, JSON examples, interoperability
Self-HostingRun OpenCap Stack on your own infrastructure

Quick Start​

Option A — Call the REST API directly:

# 1. Get a token
TOKEN=$(curl -s -X POST https://api.opencapstack.com/api/v1/auth/login \
  -H "Content-Type: application/json" \
  -d '{"email":"you@example.com","password":"yourpassword"}' \
  | python3 -c "import sys,json; print(json.load(sys.stdin)['token'])")

# 2. Query the cap table
curl https://api.opencapstack.com/api/v1/stakeholders \
  -H "Authorization: Bearer $TOKEN"

Option B — Use the MCP server from Claude:

npm install -g @opencapstack/mcp-server

Then in Claude: "Show me the cap table summary" — and it just works.

→ See the MCP Server guide for full setup.