How to evaluate a research peptide supplier
A practical checklist for judging a source yourself, before money changes hands.
The short version
The single most useful signal is a batch-specific certificate of analysis from an independent lab, one whose lot number and date match the exact product you are buying. Everything else, company transparency, clear policies, sensible storage and shipping, supports that. A shiny site, a big purity number with no test method, or a five-star review is not evidence. This page lists what to check, and how we apply the same criteria before we reference any vendor.
Third-party testing, not just an in-house claim
Ask for a certificate of analysis, and prefer testing done by an independent lab rather than only the seller’s own report. The COA should name the compound, show a purity figure, and state the method used, usually HPLC for purity and mass spectrometry for identity. A purity percentage with no method behind it tells you very little. Our COA guide walks through how to read one.
Make the COA match the product
A real COA is tied to a specific batch. Check that the lot number on the COA matches the lot on the vial or listing, that the test date is recent, and that the compound and vial size line up. A COA for a different lot, or one with no lot number at all, is close to worthless. If a vendor cannot produce a batch COA on request, treat that as a hard no.
Company transparency
Look for a real company identity and a way to reach a person, clear shipping and storage information, and plain refund or replacement policies. Cold-chain handling matters for peptides, so a vendor that ships and stores correctly is worth more than one that is simply cheap. Vague ownership, no contact route, or no policies are all reasons to walk.
Red flags
- Medical or human-use claims, or before-and-after results
- A purity number with no test method, or no COA at all
- A COA whose lot number or date does not match the product
- Prices far below everyone else, which often signals underdosing or impurity
- Pressure tactics, fake scarcity, or reviews that cannot be verified
How we apply this
We reference vendors as a convenience, not an endorsement, and we hold them to the checks above rather than to a logo or an affiliate relationship. A link here means a vendor is one we reference, not that we vouch for any single batch you receive. Always run the same checks yourself, since quality is set batch by batch. See our sourcing and standards for how the whole site is built.