A workbook is a value you can commit, diff and recompute.
Canonical JSON in, canonical JSON out. Put the model in version control, review a change to it the way you review code, and recompute it later with a pinned clock, timezone and seed to get the same grid back.
Shipped for the engine and the workbook format. The explainability layer above it — showing how a number was derived — is not released.
Edit any cell — it recalculates here, live
Worked examples
Two things you can do right now.
An amortisation schedule that computes the same way twice
The same workbook plus the same pinned context is the same grid, today and in five years. That is the property that makes a number defensible rather than merely plausible.
Open the demo →Review a change to a model the way you review code
A workbook serialises to RFC 8785 canonical JSON. Two people who build the same model get byte-identical files, so a diff shows what actually changed instead of what the spreadsheet happened to reorder.
Open the demo →Not quite your problem?
The same engine sits under all of these. The difference is only which surface you reach for.