KSeF Express – Konwersja faktur do FA(3) XML - Sell Project
Listed March 20, 2026
About KSeF Express – Konwersja faktur do FA(3) XML
Validated FA(3) KSeF invoice engine for Poland's April 2026 mandatory deadline.
KSeF Express is a validated FA(3) XML invoice generation engine built for Poland's mandatory KSeF e-invoicing rollout. From April 1st 2026 over 1.5 million Polish businesses are legally required to issue invoices through the KSeF system. The tool passes both Sorgera XSD validation and the official Ministry of Finance KSeF portal sandbox. It solves the exact schema errors that crash most existing generators including the non-obvious Adnotacje sequence logic and Podmiot2 structure that trip up standard libraries. Supports the 10 most common invoice types for Polish SMEs including standard B2B 23% VAT, reduced rates at 8% and 5%, zero-rated, VAT exempt, simplified invoices, advance payments, final invoices and corrections. Built in TypeScript and React with an Express.js backend. Google login via Firebase, Stripe subscription payments integrated with two tiers — 119 PLN (30.79 USD) month for up to 50 invoices and 239 PLN/month for unlimited invoices. Live in production today at ksef-express.vercel.app. Full codebase, IP, domain and live deployment included in the sale. Handover completable within 72 hours.
Next step: <p>Expand to all 50 KSeF invoice types, integrate with Polish ERP systems, target accounting firms as resellers, expand to other EU countries with upcoming e-invoicing mandates including Germany and Romania. First mover advantage expires April 1st 2026. New owner should onboard customers immediately</p>
For sale
Asking price: $15,000 USD
What's included
Domain name, Source code, All related data, All related design work
Live Vercel deployment, Render backend, Firebase project, Stripe integration, Firestore database, full IP transfer.
Reason for selling
Expand to all 50 KSeF invoice types, integrate with Polish ERP systems, target accounting firms as resellers, expand to other EU countries with upcoming e-invoicing mandates including Germany and Romania. First mover advantage expires April 1st 2026 — new owner should onboard customers immediately.
Project metrics
Average Monthly Visitors: Under 1K/mo
Average Monthly Revenue: Pre-revenue
Average Monthly Downloads: Pre-launch / New project
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