Check a certificate.
Type the number printed on the certificate, or scan its QR code. You'll see in a second whether it is genuine and valid.
What this check shows
Only what an employer needs to know it is genuine: the number, the name, the course and its topics, the date issued, and whether it is valid.
It never shows the test score, study time, sector, email or payment. A cancelled certificate (for example after a refund) shows as not valid.