A certificate is only worth as much as its verifiability. A PDF anyone can edit proves nothing.

Give every certificate a unique, unguessable identifier and a public verification page that confirms the holder, course and issue date straight from your database. Sign the payload so any tampering is detectable, and keep the design clean and printable.

Don't over-engineer: you rarely need a blockchain for this. A signed record plus a public verify endpoint covers the vast majority of cases, is cheap to run, and is trivial for an employer to check. Reserve on-chain anchoring for contexts that genuinely demand it.

Render the certificate as crisp vector (SVG) so it scales from a screen to a printed wall. Include the verification URL as text and, optionally, a QR code — the easier it is to check, the more the certificate is worth.