A private, offline debt-payoff cockpit — one file that lives on your computer, no account and no cloud. List every debt, set a monthly payment budget, pick a strategy, and DebtOS shows you the exact road to zero: which debt falls first, your debt-free date, and how much interest your plan saves versus paying minimums alone. Log a payment and your balances move themselves — nothing needs a second manual edit.

The whole app is built around one arc: debt down to zero. The Dashboard leads with what's left of what you started with, a payoff ring, a debt-free countdown, and a milestone wall that fills in as you go.

Your purchase is three files: the DebtOS.html app, The Payoff companion book, and a Quick Start PDF. Nothing to install — double-click DebtOS.html and it opens in your browser (Chrome, Safari, Edge, Firefox). It works fully offline once loaded, on Mac or Windows, and needs no account or signup.

First time in, you'll see two choices: ✨ Explore with sample data loads a full example plan (the Rivera family, six debts, a real strategy already running) so you can see every screen populated. ＋ Add my first debt skips the demo and starts your own plan. Switch anytime — while exploring the demo, a banner up top offers Start fresh with my own, which clears the sample data.

Dashboard — remaining balance against your starting total, a payoff ring, a debt-free countdown, and a burn bar of every debt shrinking to zero. Below: your on-time streak, what falls next, this month's payment, and interest saved vs. minimums-only.

Debts — your creditor directory. ＋ Add debt to enter name, type, APR, balance, minimum payment, credit limit and due day. Balances are live — logging a payment moves them for you; edit a debt directly only for a correction.

Payment Plan — set your monthly payment budget and strategy (Snowball, Avalanche or Custom). Once budget is set, see exactly what to pay each debt this month, plus the full schedule to zero — click show schedule on any debt for its amortization table.

Strategy Lab — Snowball, Avalanche and Custom side by side on your real numbers, with the exact debt-free date, time and interest difference between them. Click Use snowball / avalanche / custom to switch.

What-If — a sandbox that never touches your real plan: try a one-off windfall, a bigger monthly payment, or a consolidation loan, and see what it would actually change.

Payments — ＋ Log payment and DebtOS splits it into interest and principal automatically, moves the balance, and updates your streak. Edit or delete any entry — deleting puts the principal back on the balance.

Milestones — the celebration wall. Debts paid off, dollar and percentage thresholds, and on-time streaks are added automatically as you hit them. ＋ Add milestone to log your own win.

Is my data private? Yes — everything stays in your browser on your device, no cloud, no account, nothing ever sent anywhere. Does it work offline? Yes, fully, once the page has loaded once. How do I back up or move devices? Settings ⚙ → ⬇ Export backup saves a small file; on the new device, Settings → ⬆ Import restores it. Will logging a payment update my balance? Yes, automatically — interest split from the APR, the rest off principal. Can I add unlimited debts? Yes, no cap on debts, payments or milestones. What currencies? $ £ € ₹ A$ C$, set in Settings. Are updates free? Yes — re-download DebtOS anytime from your Etsy purchases page.

Data not saving? DebtOS saves to your browser's local storage, which private/incognito windows wipe on close — open it in a normal window. If storage is full, export a backup from Settings and clear some space. Moving to a new computer? Export a backup on the old machine, copy DebtOS.html and the backup file to the new one, open the app, and Import. Starting over? Settings → Reset erases everything — export a backup first if unsure, it can't be undone. Want a paper copy? Settings → 🖨 Print hides the navigation automatically so only your data prints.

DebtOS by CalmNCalculated · calmncalculated.com · Free updates — re-download anytime from your Etsy purchases. From the same money line: BudgetOS · HomeOS.