A lightweight financial planning tool that projects portfolio growth to retirement and lets you stress-test the assumptions. Plug in your numbers — income, contributions, expected returns, loans, kids’ education costs — and it charts where you’ll land.

Three lenses make it useful beyond a basic compound-interest calculator: Coast FI (when can you stop contributing and still hit your target), withdrawal rate analysis (how long your portfolio lasts after retirement), and scenario comparison (what happens if you retire earlier, save more, or returns dip).

Everything runs in the browser with no backend — just a single HTML file, Chart.js for the graphs, and localStorage to remember your inputs between sessions.