Check of ciunkos.com/ksef-invoice-validator

Oct 21, 2026, 20:35 · manual

Score: Lighthouse-style estimate, without Speed Index. TBT is the lab stand-in for INP, which needs real interactions.

LCP element: p.lead Your own system, OMS or SaaS now has to send invoices to KSeF. Drop an FA(3) XML here: it is checked against the official schema in your browser, every error is
Page weight: 30 KB
Long tasks: 1
Conditions: 412×823, DPR 1.75, CPU slowed 2×, 150 ms latency, 1.6 Mbps down, 750 kbps up, no cache, 3 loads, median

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