The Actuarial Engine

A giant actuarial spreadsheet, reborn as software.

Tech Working prototype Client work · shown re-skinned

1:1

parity with the workbook

tools in the suite

3-up

plan comparison, the hero view

The problem

The organization's most important math lived in a workbook only two people could safely touch, emailed around with filenames like FINAL-v7-REALLY.xlsx.

Porting it meant proving the web version computes exactly what the spreadsheet computes — close isn't good enough in actuarial work.

What we built

The whole calc engine re-implemented in TypeScript, tested against Excel-verified values so the port can't quietly drift.
A data-prep pipeline with a pinned random seed, so the underlying tables are reproducible to the byte.
Eight tools including a three-plan side-by-side comparison with a live actuarial-value meter.
Excel's visual language kept on purpose — a yellow cell still means 'type here' — so the two experts felt at home on day one.

TypeScript calc engineExcel-parity testsPython data prepNo backendEight-tool suite

In the product

Three plans, side by side

AV Engine

PlansCopilotGroups

Silver 3500AV 71.2%

Deductible$3,500

OOP Max$8,200

Coins.30%

Gold 1500AV 79.8%

Deductible$1,500

OOP Max$6,000

Coins.20%

Platinum 500AV 88.4%

Deductible$500

OOP Max$3,800

Coins.10%

Navy and gold with metal-tier chips — the spreadsheet's soul, the web's manners.

The meter

AV Engine

AV CalcSnapshotStop-loss

79.8%Actuarial value

GoldMetal tier

±0.0Drift vs workbook

InputDeductible changed — engine re-ran in 4mslive

ParityAll verified test values passing✓

Every input change re-runs the engine; the meter answers instantly — no recalculating, no #REF!.