The archive · Product Ideas · Product decision · 2024
Startup Funding Simulator turns opaque SAFE math into a visual dilution sandbox
A simulator shows founders how each SAFE, priced round and option pool moves their ownership — open-sourced because the builders could not find one.
Funding Simulator
What it had to solve
The builders were fundraising for their own company and expected 'just an Excel sheet', but post-money SAFEs, discount-versus-cap conversions, circular option-pool math and pro-rata rights turned out to be genuinely hard to model. They signed up to Pulley, Carta and other simulators and found them confusing.
How it works
The builders were in the middle of raising money for their own company when they discovered that 'just an Excel sheet' was not how modern fundraising works. Post-money SAFEs convert at the first priced round but in different ways — discount, valuation cap, both, or an MFN clause — all SAFEs convert together without diluting each other, and an investor-demanded option pool creates a circular calculation that even Y Combinator's own explainer avoids showing.
So they built a simulator rather than another calculator. A raise is a timeline: you add SAFEs, priced rounds and employee option grants as steps, and every step re-draws the cap table and the founder's ownership, with an exit scenario at the end showing what the founders keep. The tool was deliberately limited to post-money SAFEs and priced rounds, listed its assumptions openly, and was open-sourced because, as the builders put it, they did not build it to make money.
Launched on Hacker News on 24 January 2024, the thread drew 654 points and 161 comments. Founders praised it as much cleaner than Carta's simulation tool, requested an employee point of view, liquidation-preference graphs and a sell-after-SAFE option, debated the calculator-versus-simulator label, and delightedly broke the math to become infinite decamillionaires — while the builder answered requests in-thread and said a SAFE-round exit was being worked on.
Why it lands
- The builders were the target user — mid-fundraise themselves — so the tool answered their own confusion instead of a guessed market.
- Representing each instrument as a visible step makes discount, cap and option-pool effects appear as ownership changes rather than abstract legal terms.
- Declaring what the tool does not model (down rounds, pre-money SAFEs) kept v1 honest instead of silently approximating the hardest cases.
- Open-sourcing removed the sales motive, letting a tool about fairness in cap tables be read as neutral rather than as a pitch for a competitor service.
What it did
Posted as Show HN on 24 January 2024, the simulator drew 654 points and 161 comments: founders called it much cleaner than Carta's simulation tool and said their co-founders would use it, while others asked for employee, liquidation-preference and SAFE-exit views, debated whether it was a calculator or a simulator, and broke it gloriously to get $Infinity exits.
What you can take
When a process's pain is comprehension rather than arithmetic, sell the seeing, not the spreadsheet: turn each opaque term into a step whose effect is visible, and the users hand you the feature list.
Since then
The thread doubled as a roadmap: the builder promised a sell-after-SAFE simulation, and commenters' requests — an employee point of view, liquidation-preference graphs and cleaner share links — were answered or logged in replies. Reviewers called it useful for quick strategy ball-parks, and the community's argument over what a simulator owes its users showed how hungry founders were for tools that explain the paper they sign. The project stayed uncommercial by design: open source, built because the authors needed it, with the code admittedly 'a mess right now' but promised to improve.
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