Reckoner Calculator
16 days
1. The Founder's Problem
82% of startups fail due to cash flow issues. Founders track runway in spreadsheets (error prone, slow). Need instant, accurate financial projections.
2. Why Traditional Solutions Failed
- ✗Spreadsheets have formula errors, no validation
- ✗Manual calculations take 20-30 min, outdated immediately
- ✗No tools give instant feedback with AI recommendations
3. What We Built
- ✓Financial engine: Burn Rate = Expenses - Revenue, Runway = Cash / Burn Rate
- ✓Scenario planning: model different growth rates, break even predictions
- ✓Dual AI (Groq + Gemini) for Pro tier financial recommendations
- ✓Interactive charts (Recharts): runway trends, break even projections
- ✓PDF reports + CSV export
4. The Process
WEEK 1
Core formulas (2 days), Validation logic (2 days), UI + charts (3 days)
WEEK 2
AI integration (3 days), Stripe setup (2 days), Usage tracking (2 days)
WEEK 3
PDF generation (1 day), Testing edge cases (1 day), Deploy (1 day)
5. Results & Metrics
users
29 signups
revenue
$0 (test mode only)
github
7 stars
performance
<1s calculations, <3s with AI, 100% accuracy vs Excel
code
97.9% TypeScript, 11 commits
6. Tech Stack & Why
Next.js 15
Server components for calculations, client for interactivity
Groq + Gemini
Groq primary (fast), Gemini fallback (accurate)
Recharts
Real time chart updates without re-renders
Stripe
Subscription model: $19/month, test mode for portfolio
7. What We Cut to Ship Fast
- —Multi-currency support (USD only for MVP)
- —Team sharing features (single user first)
- —Historical data tracking (focus on current runway)
8. Lessons Learned
- →Financial apps demand precision. Rounding errors compound fast.
- →Instant feedback (<1s) is non negotiable. Users expect calculator speed.
- →AI recommendations need domain specificity. Generic advice = useless.
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