CertCheck - A lookup and verification utility for Graded Card certificate information - CGC, PSA, SGC, and more grading companies.

Before purchasing your next graded card, it's a good idea to double check it's certificate info. This helps you validate all the details about the card you're about to spend hard-earned money on, and it can also warn you if the cert has become invalidated in the case that it was determined to be fake or altered after the fact.