KSeF integration and a 40× faster data loader

// The problem

TrafinOil had to connect invoicing to Poland's mandatory KSeF government system — where a mistake means a rejected or duplicate invoice and trouble with the tax authority — while also cutting a nightly data loader that ran for 20 hours and blocked morning reporting.

// The solution

We built a production KSeF integration that survives the reality of the government portal: a state machine that respects the authority's rate limits, idempotent submission and four self-healing recovery paths for stuck, rejected and duplicate invoices — never a lost number. It runs multi-tenant across Poland and the Czech Republic, syncs bidirectionally with the ERP (Business Central) and is backed by an offline-capable driver mobile app. We rewrote the data loader to batches and parallelism — from 20 hours to 30 minutes.

// Results

Hundreds of thousands of invoices filed through KSeF — 100% delivered
Self-healing invoicing — stuck and duplicate invoices reconcile themselves
Bidirectional ERP (Business Central) sync + driver mobile app
Nightly data processing from 20 hours to 30 minutes (40×)

// Key metrics

Nightly data processing

Before 20 h After 30 min

40×

Invoices through KSeF

After 100,000s+

// Technologies

.NETKSeFFlutterSQL ServerRedisAzure

// CTA

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