Why I Built This — Downslope

Why I built this

I built Downslope because I'm in the same situation as a lot of people who will find it.

I'm carrying debt. Not the abstract kind you read about in case studies — real balances with real interest charges showing up every month. I know what it feels like to open a statement and watch the interest charge eat most of your payment before a dollar touches the principal.

When I started looking for a calculator that could actually help me plan, I kept running into the same problems: tools that locked the useful features behind a paywall, tools that couldn't handle a 0% promotional card correctly, or tools that gave me a number without explaining how they got there.

So I built one.

What I bring to it

I'm not a random person who spun up a calculator over a weekend. I have a finance background and spent a lot of time making sure the math is right before I let anyone else use it.

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Education

MBA, 4.0 GPA — Grand Canyon University

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Validation

Tested against Excel amortization

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Privacy

All math runs in your browser

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Experience

Finance background, paying off debt myself

The calculations have been validated against Excel's NPER and CUMIPMT functions across multiple scenarios. You can see the exact test cases on the About the Math page.

Why I'm telling you this

The personal finance space is full of tools that look helpful but exist to collect your email or sell you something. I've used them. I know what they feel like.

Downslope is different in one important way: your debt data never leaves your device. Nothing is sent to a server. Nothing is stored anywhere but your own browser. The only exception is the AI game plan feature, which sends an anonymized summary of your balances and rates to Anthropic — and that's clearly labelled when you use it.

An honest note on the Pro features. The free version is genuinely complete — unlimited debts, avalanche vs. snowball comparison, charts, interest savings. Pro adds scenario modeling, cash-flow planning, an editable schedule, promo expiration tracking, printable reports, CSV export, and an AI-generated game plan. I'm not hiding useful things behind a paywall. The free tier is what I would have wanted when I first started looking for help.

What I promise

My commitments to you

The math is correct. If you find a calculation that doesn't match Excel, I want to know and I'll fix it.
No dark patterns. No countdown timers, no fake urgency, no hiding the cancel button.
Affiliate links only when they help. If I ever recommend a balance transfer card or a refinance product, it's because the numbers say it saves you money — and I'll show you those numbers.
Your data stays yours. I have no ability to see your debt information. It lives in your browser and nowhere else.

I'm paying off debt with this tool. If it stops being useful to me, I'll say so. If I find a bug in the math, I'll fix it publicly and document what changed.

That's the deal.

Start your payoff plan About the math →

Downslope is a planning tool, not financial advice. I'm not a licensed financial advisor. The calculations are accurate, but your actual payoff timeline depends on your lender's billing cycle, minimum payment recalculation rules, and any fees not entered here. When in doubt, verify against your actual statement.