Payoff Lab
Your cards as they actually are go in; the month you are debt-free, and what avalanche saves over snowball, comes out.
Your complete payoff schedule and debt-free date, promo cliffs included.
Payoff Lab is free to use today, and there is nothing to buy. A paid tier is planned at $19 one-time — it would add: PDF and CSV export of the full schedule, saved side-by-side scenarios, and promo-cliff reminders.
It isn't built, so there is no checkout on this site and no way to be charged. When it exists it will appear on the updates page, with the date.
Email support@avyth.com and the person who built Payoff Lab reads it. If it fails on your file, say what the file looks like — that is usually enough to fix it.