Ship the spreadsheet instead of rebuilding it.
Your users already know VLOOKUP. Embedding an engine that matches the sheet they came from is less work than reimplementing a hundred functions and defending the rounding.
The engine is MIT and on npm today. The React component is not published yet — it is pre-1.0 and we would rather talk to you than hand you an unstable API.
Edit any cell — it recalculates here, live
Worked examples
Two things you can do right now.
A pricing calculator your users can check
Tiered per-seat pricing with an annual discount — the calculation every B2B product puts on a page, usually reimplemented in JavaScript and then quietly disagreeing with what billing charges.
Open the demo →A data grid whose cells are formulas
A table of line items where the totals are computed by a real spreadsheet engine rather than by your reducer — and where a user can type a formula into a cell and have it mean what they expect.
Open the demo →Not quite your problem?
The same engine sits under all of these. The difference is only which surface you reach for.