The pharmacies we work with are licensed 503A and 503B compounding pharmacies based in the US, and all compounding happens in the US. The active pharmaceutical ingredients (APIs) come from FDA-registered facilities with proper documentation, which is what separates regulated compounding from gray-market peptide sourcing.
The pharmacies test compounded products for potency, sterility, and identity against the standards required for their license: USP standards for 503A pharmacies, and cGMP for 503B.