How do I verify a private label cosmetic manufacturer is legitimate and GMP-certified?

Ask for their FDA facility registration number, ISO 22716 (GMP) certification, and references from existing indie brand clients. Request a certificate of analysis (COA) from a recent batch and confirm they conduct preservative efficacy testing. On the AJ Cosmo Labs platform, manufacturers are credentialed before listing, which reduces the due-diligence burden for indie founders significantly.