Stack & Borrow

Bitcoin-backed loan calculator. Sats-first, tax-aware, with honest lender ranking — now in the receipt booklet aesthetic.

What's in this folder

stack-and-borrow/
├── index.html ← page shell the browser loads
├── package.json ← lists dependencies
├── vite.config.js ← build config
├── public/
│ ├── favicon.svg ← bitcoin logo
│ └── lenders.json ← lender data — EDIT THIS to update rates
└── src/
├── main.jsx ← starts the React app
├── App.jsx ← router + error boundary
├── lib/
│ ├── format.js ← display helpers (fmtNum, fmtSats, fmtMoney…)
│ ├── math.js ← loan-math primitives + lender ranking
│ └── hooks.js ← useLivePrices, useLenders, usePersistentState
├── system/
│ ├── tokens.js ← colors, fonts, currency metadata, profiles
│ └── components.jsx ← PaperFrame, BrandHeader, DashedRule, Row…
└── pages/
├── Calculator.jsx ← the main app (loan input → estimate → lenders)
├── Lenders.jsx ← full directory, filterable, ranked
└── About.jsx ← terms of philosophy / FAQ

How to run it on your computer

You need Node.js installed. Get it from https://nodejs.org (the LTS version).

Open a terminal in this folder and type:

npm install
npm run dev

It will print a URL like http://localhost:5173. Open that in your browser.

To stop, press Ctrl + C in the terminal.

How to build for production

npm run build

This creates a dist/ folder with everything you need to upload to Cloudflare Pages, your StartOS, or any web host.

How to update lender rates without touching code

1. Open public/lenders.json in any text editor
2. Change rates, terms, or whatever needs updating
3. Update the lastUpdated date at the top
4. Save the file
5. If running locally — refresh the browser. If on Cloudflare Pages — commit and push to GitHub, deploy is automatic.

Routes

URL fragment	Page
/ or #	Calculator (default)
#lenders	Full lenders directory
#about	Terms of philosophy

Hash routing — no server config required. Works on any static host.

What's new vs the previous version

• New visual language: cream paper, warm-black ink, muted bitcoin orange. Inspired by printed loan slips and editorial pamphlets.
• New page: dedicated #lenders directory with filters (US / EU / NO REHYPO / MULTISIG).
• Lender ranking math: now correctly resolves rate tiers per loan size for Strike, Ledn, and Arch (previously a flat rate was used).
• No recharts dependency: projection chart is now inline SVG (smaller bundle, faster paint). You can remove recharts from dependencies if you like.
• Modular source: the original 2,000-line App.jsx is split into lib/, system/, and pages/ for maintainability.

License

Your code, your call.