SWAG Estimates

Multi-tenant SaaS for industrial construction estimating. It replicates an Excel estimating workbook in the browser: the workbook is extracted once into a JSON schema, IronCalc recomputes every formula client-side via WebAssembly, and only user-entered cell values are stored — as a diff against the schema rather than a full copy of the sheet.

How it works

• Workbook as schema — the source Excel workbook is extracted once into a JSON schema that defines the sheet structure and formulas.
• Client-side recalculation — IronCalc (MIT / Apache-2.0) runs as WASM in the browser and recomputes formulas without a server round trip.
• Diff-based storage — only the cell values a user actually enters are persisted, keeping stored estimates small and the schema authoritative.
• Fidelity verification — a server-side verifier uses IronCalc's native Node bindings to confirm browser results match the original workbook.

Stack

• Next.js 16 — App Router; proxy.ts handles optimistic auth redirects, with real enforcement in src/lib/auth/dal.ts
• Auth.js v5 — JWT sessions via the credentials provider; signup creates a User, a Tenant, and an OWNER Membership

Guides

Guide	What it covers
Working with estimates	Creating, duplicating, the grid, offline sync
Workbook templates	Uploading workbooks and fidelity verification
Your workspace and team	Sign-in, passkeys, members, and billing