About PEM Validator
A PEM key that looks fine to the eye - right header, right footer, plausible Base64 in between - can still fail to import if it's the wrong format (SPKI vs PKCS#8) or subtly corrupted.
Paste a PEM block and this attempts a real Web Crypto import to confirm it's actually parseable RSA-OAEP key material, rather than just checking that it looks like a PEM at a glance.