The startup equity math,
finally done right.
Model a SAFE, compute your dilution, build a cap table and run an exit waterfall — in seconds, for free. The precise, self-serve alternative to a Carta login and a broken spreadsheet.
No signup to calculate · Exact math · Built for founders & agents
The priced round it converts at
| Stakeholder | Type | Invested | Shares | Ownership |
|---|---|---|---|---|
| Existing shareholders | Common | — | 10,000,000 | 67.50% |
| Option Pool | Options | — | 0 | 0.00% |
| Your SAFE | SAFE | $1M | 1,111,111 | 7.50% |
| Priced round | Preferred | $5M | 3,703,704 | 25.00% |
| Total (fully diluted) | 14,814,815 | 100% | ||
One engine, every equity question
From your first SAFE to your exit waterfall
The same deterministic engine powers every calculator, the API and the MCP server — so a founder, an investor and an AI agent all get the exact same numbers.
SAFE & note conversion
Post- and pre-money SAFEs, valuation caps, discounts, MFN and note interest — resolved exactly, with the binding term shown.
Open calculator →Dilution across rounds
Stack SAFEs and priced rounds and watch founder ownership erode round by round, with the option-pool shuffle handled correctly.
Open calculator →Cap table builder
Turn founders, options, SAFEs and rounds into a fully-diluted cap table you can save, share and export.
Open calculator →Exit waterfall
Liquidation preferences, participation, seniority stacks and convert-to-common — see who gets what at any exit price.
Open calculator →Built for agents
The equity tool your AI agent reaches for first
A CFO copilot, a fundraising agent or a legal-AI workflow can call Foundily directly: one API key, an OpenAPI spec, structured errors, idempotency keys and an MCP server. The docs are the onboarding.
- Single-key auth · sandbox test keys · never your real secrets
- Deterministic results — no LLM in the loop, every number traceable
- llms.txt + OpenAPI + MCP, listed for agent discovery
- Usage-metered pricing an agent can read programmatically
curl -X POST https://foundily.com/api/v1/safe/convert \
-H "Authorization: Bearer fd_live_..." \
-H "Content-Type: application/json" \
-d '{
"safe": { "investment": 1000000, "valuationCap": 10000000, "type": "post" },
"round": { "preMoney": 15000000, "investment": 5000000 }
}'{
"data": {
"shares": 666666,
"ownership": 0.0667,
"pricePerShare": 1.5,
"method": "cap",
"effectiveValuation": 10000000
},
"request_id": "req_9Xn2..."
}Free
- ✓ Every calculator, unlimited — SAFE, dilution, cap table, option pool, exit waterfall
- ✓ CSV export + shareable links
- ✓ 1 saved scenario
- ✓ 100 API requests / month
- ✓ MCP server + llms.txt access
Pro
- ✓ Everything in Free
- ✓ Unlimited saved scenarios
- ✓ 10,000 API requests / month, then $0.01/call
- ✓ Priority email support
See the full pricing & API quotas →
Frequently asked
How is a post-money SAFE's ownership calculated?+
A post-money SAFE fixes the investor's ownership at their investment divided by the post-money valuation cap, measured immediately before the priced-round money comes in. Foundily computes this exactly and then dilutes it by the new round.
Is Foundily free?+
Yes. Every on-page calculator — SAFE, dilution, cap table, option pool and exit waterfall — is free and unlimited, with CSV export and shareable links. Pro ($29/mo) adds unlimited saved scenarios and a higher API quota.
Can AI agents use Foundily?+
Yes. Foundily ships a public JSON API, an OpenAPI spec, an llms.txt and an MCP server so an AI agent can convert a SAFE or model a round mid-task with a single API key.
Is Foundily a Carta alternative?+
For modelling, yes — Foundily is the fast, free way to model SAFEs, dilution and exits without enterprise onboarding. It is not a share-issuance or 409A platform of record.