Open Source Debt Payoff Planner Template
Snowball or avalanche? Run both. Keep the cheaper one.
A debt snowball and avalanche calculator: list your debts, set an extra monthly payment, and compare payoff time, total interest, and payoff order side by side.
This is the real app, not a mockup. Whatever you enter in the demo stays in your browser and belongs to nobody.
What you get
One zip. Everything to own it.
Debt Payoff Planner answers the question every payoff journey starts with: snowball or avalanche? List each debt with its balance, APR, and minimum payment, choose how much extra you can put in monthly, and the planner runs a real month-by-month simulation of both strategies — monthly compounding, minimums first, rollover payments attacking the target debt — and shows debt-free dates, total interest, the payoff order, and exactly how much the avalanche saves. If minimums can't outrun the interest, it says so instead of pretending. Your numbers never leave the browser, which is precisely where debt numbers belong.
- Side-by-side snowball vs avalanche comparison
- Real month-by-month simulation with monthly compounding
- Debt-free date, total interest, and payoff order per strategy
- Rollover payments modeled honestly
- Warns when minimums can't outrun the interest
debt-payoff-planner/├── app/the running Next.js app├── agent/START_HERE, PROJECT_MAP, RULES, RECIPES, TESTS, DEPLOY├── CLAUDE.mdread automatically by Claude Code├── AGENTS.mdread automatically by Codex├── .cursor/rules/loaded automatically by Cursor└── README.mdrun it, then make it yours
Inside the app
Customize with AI
Your agent already knows this codebase.
Ships with CLAUDE.md, AGENTS.md, Cursor rules, and a full agent handbook — project map, safety rules, recipes, tests, and deploy notes.
Prompts written against this app
Run it
5 min to your own copy.
- 01Create your editable app copy and unzip it.
- 02Run npm install.
- 03Run npm run dev and open http://localhost:3000.
- 04Read /agent/START_HERE.md before customizing.
- 05Swap the local-first storage boundary for your own backend when ready.
Debt Payoff Planner data stays in this browser by default.
No account, backend, or cloud sync is included in the current package.
An agent can add optional sync later while preserving the local-first default.
This package is standard-ready for Create My App and AI customization.
A full app-only PWA install route is not enabled yet for this app.
If this isn’t quite right
Take Debt Payoff Planner and make it yours.
Free, MIT, 5 min to running. The demo above is exactly what lands in your folder.