Frequently asked questions
Short answers, with links to the full explanation where one exists.
Do you test the peptides yourselves?
No. We read each vendor's public pages, including any certificate of analysis they publish, and score what they document. We have not run our own lab tests on any product.
What does a vendor's rank actually mean?
It's a documentation score, not a safety or quality score. We check three things on every vendor: whether an outside lab wrote the purity report, whether the report names the batch you would receive, and whether the testing method is stated. Each is a pass, a partial or a fail. See the method section on the homepage, or the full vendor comparison.
Do affiliate commissions change a vendor's rank?
No. Some of our links are affiliate links, and we may earn a commission if you buy through one. We are an affiliate partner of two of the four vendors we review, and the vendor with the most public paperwork, Peptryn, is a third that does not pay us the most. Our partner American Peptides ranks above our partner Core Power Peptides on documentation. See our disclosure.
If Core Power Peptides isn't ranked first, why do you feature it so heavily?
Two different questions get two different answers on this site. "Who publishes the most complete documentation?" is answered by the ranked table, in order, and Core Power Peptides is third of four there; see the full comparison. "Who do we send readers to buy from?" is a separate, commercial decision, and we made it in Core Power Peptides' favor for reasons that are not about paperwork: the widest catalog of the four, competitive pricing, stated US manufacturing, and a transparent 25% affiliate program. That is a business relationship, not a documentation score, and we say so plainly rather than blur the two.
Does Core Power Peptides sell retatrutide?
No, not as of our last check. It sells tirzepatide, a dual GIP/GLP-1 receptor agonist that its own product page describes as a benchmark compound for the newer triple-agonist class that retatrutide belongs to. If you want retatrutide itself, Peptryn stocks it directly, with two batch-matched certificates, and ranks first of the four vendors we check on documentation. American Peptides, which we added on 8 October 2026, lists it too. See our guide on what "dual" and "triple" agonist means for how the two compounds relate, and our tirzepatide page for the compound we feature by default.
What does "research-use-only" mean?
Less than most buyers assume. It borrows the wording of an FDA rule written for diagnostic devices, not for peptides, and the FDA has repeatedly rejected it as a defense when a seller's own marketing shows a product is intended for a person to use. Read the full guide: what research-use-only labeling does and does not mean.
Is it legal to buy research peptides?
We're not a law firm, and this isn't legal advice; that depends on your own situation and jurisdiction. What we can tell you is that a "research use only" label on a product does not, on its own, settle the question, which the guide above covers in more detail.
Do you recommend a peptide, a dose, or how to use one?
No, and we won't. Research peptides are sold for laboratory research. Nothing on this site is medical advice, and no page describes results for the body. Talk to a qualified clinician before making any health decision.
How often do you recheck a vendor?
Vendors change their sites, so a review is a snapshot. Each review and the homepage table state the date we last checked. We revisit vendor pages periodically and update a review when something material changes.
I think a review is wrong. How do I tell you?
Contact us with the page and the document that shows otherwise. We correct verified errors and note the date of the change.