Executive summary
PlusOne modernization moved a legacy engineering-calculation application toward a production-ready SaaS product. The work preserved engineering calculation intent while introducing a workspace model, project management, version history, permissions, exports, and a commercial product surface.
Calculation workflow
Engineers can organise projects and calculations in shared workspaces, then review inputs, outputs, charts, versions, and exports from a single workflow.
The modernization treats validation as part of delivery. Typed inputs, units, dropdown mappings, golden fixtures, tolerance checks, warning codes, and row-by-row comparisons help protect numerical parity with legacy behaviour.
Platform and commercial foundation
The product replaces file-system fragility with PostgreSQL-backed projects, calculations, settings, versions, charts, and exports. That foundation enables history, sharing, permissions, search, auditability, and recovery.
The SaaS model supports free, professional, and enterprise plans, with room for module pricing, usage controls, integrations, APIs, MCP, and professional reporting outputs.
Outcome
The result is a controlled path from legacy calculation logic to a scalable engineering product: preserve trusted outputs, make validation visible, and add the governance needed for teams and enterprise deployment.