KSeF API Gateway
Integration gateway for Poland's National e-Invoicing System — simplified REST API, monitoring, queuing, and automatic retry.
What is KSeF API Gateway?
KSeF API Gateway (ksefapi.com) is a middleware layer between your system and the National e-Invoicing System (KSeF) operated by the Polish Ministry of Finance.
Instead of integrating directly with KSeF — which requires handling session tokens, complex XML structures, XAdES signatures, and unstable government responses — you use a single, consistent REST API.
What you get
- Simplified API — REST JSON instead of SOAP/XML
- Automatic retry — resilient resubmission on KSeF errors or downtime
- Queuing — bulk invoice submission with throughput control
- Monitoring — real-time invoice statuses and webhook notifications
- Validation — invoice verification before sending to KSeF
- Multi-tenancy — one API account, multiple companies (NIPs)
Environments
| Environment | API URL | Auth URL |
|---|---|---|
| Demo | https://demo.ksefapi.com | https://demo-auth.ksefapi.com |
| Production | https://gateway.ksefapi.com | https://auth.ksefapi.com |
Next steps
Start with Getting Started for a 5-minute quickstart, or jump to Authentication for full integration details.