DEV3 Mortgage and Rent vs Buy Calculator — Source Code (React + Tailwind)

Source code of the DEV3 Mortgage and Rent vs Buy Calculator, a mortgage calculator with an amortisation schedule, extra payments and a rent-versus-buy net worth comparison over a chosen horizon.

Download: buy a licence and the ZIP is waiting in Account → Downloads. Try it live: https://dev3.tech/tools/mortgage-rent-vs-buy-calculator shows the finished tool running.

What is in the download

• A standalone Vite + React + TypeScript + Tailwind CSS project: src/tool holds the tool, shared pieces sit beside it
• package.json with exact versions plus a lockfile, so npm ci works
• README.md (run, build, embed in Next.js or plain React) and an MIT LICENSE

What the code does

• Monthly amortisation with extra payments and interest saved
• Yearly and monthly schedule views with CSV export
• Rent vs buy model with property tax, maintenance, insurance and transaction costs
• Break-even year and SVG net worth chart

Tech stack

React 19, TypeScript, Vite, Tailwind CSS 4.

Install and customise

The How to install and How to use tabs list the steps. In short: unzip, npm ci, npm run dev, then copy the tool folder into your own app if you want to embed it.

Good to know

• A browser-only tool: there is no backend or database in the code.
• Ignores mortgage tax relief, capital gains tax and variable rates.