CSV Column Formula

Add a derived column to a CSV by applying a JavaScript math expression that references other columns by name. Type the new column's name and a formula like price * quantity, subtotal * (1 + tax_rate), or Math.round(amount / 100) / 100 — column names become variables (spaces and dashes become underscores). Numeric strings are coerced; non-numeric cells stay blank. Handles quoted fields and embedded newlines. Everything runs locally in your browser.