Start with documentation, not price
The single biggest factor in a safe purchase is whether the seller can produce a batch-specific certificate of analysis (COA) for the exact vial you’d receive. Price comparisons matter far less than this one check, since an unusually cheap listing with no COA isn’t actually a bargain if there’s no way to confirm what’s in the vial.
What “batch-specific” means
A COA tied to the specific batch, with a lot or batch number that matches what’s printed on the vial, is meaningfully different from a generic COA reused across every listing on a site. Only the former actually verifies what you’d receive.
Delivery and handling
Because peptides degrade with heat exposure, how an order ships, insulated packaging, ice packs, same-day dispatch, matters almost as much as the lab documentation. A seller who’s thought through both testing and shipping is demonstrating a more complete, trustworthy process than one who’s only got one half right.
Communication before you order
A seller who answers direct questions about testing, batch numbers, or shipping clearly and specifically, before you’ve paid anything, is a stronger signal than glowing but vague marketing copy.
A simple starting checklist
Batch-specific COA available. Clear shipping and handling practice. Responsive to direct questions. Consistent, verifiable business presence rather than a one-page site with no other information.