Fisklmate

The problem

Small companies in Germany run payroll, bookkeeping and planning in separate tools and send spreadsheets back and forth with their tax advisor. Fisklmate puts all of it in one web app that both sides use.

What I built

• Real-time data layer. Reads stream from Postgres through Electric SQL. Writes go through tRPC and return the Postgres transaction ID, so optimistic updates in the UI settle against the confirmed data. Rows are filtered per role on the server.
• Planning engine. A formula language with its own Pratt parser, a dependency graph and a web worker that recalculates forecasts off the main thread.
• Payroll integration. A layered client for the Paychex Europe API with a single boundary for cents/euro conversion, bounded fan-out and a role check on every server function.
• AI assistant. Actions that change data need approval, sensitive actions are gated and every action is audited.
• Releases. Tag-based production deploys that promote the image staging already tested.