Personal finance,worked at depth.
Most finance sites hide the spreadsheet. Here it's the entire point. The same topics you'll find anywhere — the time value of money, index funds, Roth conversions, safe withdrawal rates — carried to the depth an engineer expects: the math shown, the assumptions exposed, every input yours to tune. Enter at first principles and work deeper through the building, or go straight to the instruments.
FEAsible
Monte Carlo retirement planning. Sample thousands of market paths, read feasibility off a percentile fan — no black-box "score."
Open the app → In Progress App · FreeFormFactor
A tax-return review you run on your own 1040. Extraction happens in your browser — the document never touches the server.
Open the app → Published JS · FreeRoth Optimizer
A 20-year bracket-stacking model: what systematic conversions cost now versus what skipping them costs your heirs.
Open the tool →