NestMathFinancial freedom shouldn't come with a subscription.
NestMath is a free, open-source toolkit for personal financial decisions. No account. No cost. Nothing tracked.
How it started
NestMath started as a buy vs. rent calculator I built to understand the real math behind buying a home. The useful tools I found were either behind paywalls, buried in ads, or missing entirely.
One calculator turned into many. The common thread: people making big financial decisions should be able to run the numbers themselves, without a subscription or an advisor.
Mission
Financial freedom and education should never be behind a paywall.
What it is
NestMath covers the financial decisions most people face: buying a home, paying off debt, understanding take-home pay, and planning savings. The tools work for individuals, households, and classrooms.
Always free
No plan, no trial, no credit card.
Open source
Every line of code is public on GitHub.
Private by design
Your numbers never leave your browser.
Common questions
Do you collect any data?
No. Everything you enter stays in your browser. Nothing goes to a server, gets logged, or leaves your device. No analytics, no cookies, no account system.
Is this really free?
Yes. NestMath runs on voluntary donations through Ko-fi. If it's useful, a coffee helps keep it running and adds more tools. Entirely optional.
Can I use this in a classroom or financial literacy program?
Yes, that's exactly what it's built for. Share it freely. No attribution required, no license to worry about.
Who built this?
NestMath is built and maintained by me, Payne Kerz. I'm a software engineer by trade. It's a personal open source project, no company, no team, no VC money.
If NestMath saved you time or helped you make a decision, a coffee goes a long way toward keeping it running.