Stop rebuilding loan and compound-interest widgets from scratch on every fintech-adjacent project. FinKit is a set of four production-ready React calculators — Loan/Mortgage, Compound Interest, Savings Goal, and ROI/CAGR — each wired to a live Recharts visualization out of the box.

Every component ships in three complete themes (Ledger: dark blues/teals · Blueprint: navy/parchment/brass · Minimal: light neutral), so you pick a look or fork one as your own starting point. Numeric inputs are decoupled from their sliders, so a client typing a precise value never gets silently clamped — a detail most calculator templates get wrong.

4 calculator components (Loan, Compound Interest, Savings Goal, ROI/CAGR)

3 CSS themes, swappable with a single import

Shared chart + input components for consistent theming

Full source, no attribution required

README + customization guide + component prop reference

Runnable demo app with a live theme switcher