If you’re asking who sells peptides, compare established labs and marketplaces, check certificates of analysis
https://medium.com/@mhrifad02/peptide-sciences-closed-its-doors-heres-how-researchers-are-reassessing-suppliers-in-2026-03af0946ec11
If you're asking who sells peptides, match up well-known labs as well as market places, check out certificates of study, check out recent customer reviews, and validate cold-chain packaging to defend stability throughout transportation.