Methodology
How prices are gathered
Every listing on PeptideCompare is entered manually from a vendor's own public storefront — the price, size, and any lab documentation shown on the product page. We don't scrape automatically or pull from an API, which means updates happen in batches rather than in real time. Each vendor page shows the date its listings were last checked. Prices, stock, and promotions on these sites can and do change between checks — always confirm the current price on the vendor's own site before buying.
The three verification tiers
"Purity claimed on the label" and "independently confirmed by a named lab" are very different things, so we don't treat them the same. Every listing gets one of three tags:
- Verified COA
The vendor names a specific third-party lab (e.g. Janoshik Analytical) and we found a working link or reference to an actual certificate of analysis on the product page — not just a claim that testing happens somewhere.
- Claimed, unverified
The vendor states a purity percentage or says the product is lab-tested, but we could not find a specific lab name, batch number, or downloadable report backing that claim.
- No documentation
Nothing about testing or purity documentation was shown on the product page at all.
Filtering by test type and lab verifiability
A COA can cover different things, and vendors don't all test for the same set. The comparison table lets you filter by which specific tests a listing's documentation actually mentions:
- COA (identity & purity) — the baseline test on any certificate of analysis, usually via HPLC: is this the right compound, and how pure is it.
- Endotoxins — only shown when a vendor explicitly mentions endotoxin testing.
- Heavy metals — only shown when a vendor explicitly mentions heavy-metal testing.
A listing missing one of these tags means it wasn't mentioned by the vendor, not that the product necessarily failed that test — absence of a claim isn't evidence of a problem, just of less documentation. Separately, a ✓ Verifiable via [Lab name] marker appears on any listing where the named lab (e.g. Janoshik Analytical) has been confirmed to publish results that can be independently checked on the lab's own site or lookup tool — this is exactly what earns a listing its Verified COA tier in the first place, so the two always go together.
Confirmed: a vendor has used another company's lab report (updated 2026-09-20)
A user flagged that PeptidesDirect links a Janoshik report on their AOD-9604 product page that is actually for a different product entirely. We opened the certificate ourselves (Janoshik task #92094, verification key AGA86378Y92U — the exact report PeptidesDirect links) and confirmed it: the certificate's Client field reads "Telegram @tracyfromqsc" and its Manufacturer field reads "QSC," a Chinese peptide reseller — not PeptidesDirect. This is not an unconfirmed or ambiguous link; it is a report belonging to a different company being presented as PeptidesDirect's own testing. See PeptidesDirect's vendor page for the full detail.
This is why we now hold every "Verified COA" tag to a stricter standard than "a named-lab link exists on the page": the certificate's Client field must name the vendor itself, not a reseller, manufacturer, or unrelated third party. A link existing is not the same as a link being correct, and a lab report is only evidence for a listing if it was actually commissioned by the vendor selling it. We can't automatically check this for every listing site-wide — it requires opening each report by hand — so a full re-audit of every remaining "Verified COA" tag against this exact standard is ongoing work, not something already done everywhere.
Once we knew to look, we found more of the same general pattern of overclaiming elsewhere: Pepspan advertises "COA on every batch," but several of its listed products are actually still "pending analysis" with no report at all. CertaPeptides publishes real COAs, but for some peptides the tested lot is a specific size while a cheaper, different size is what shows at the advertised price. Those two are downgraded to "Claimed, unverified" pending individual re-confirmation; PeptidesDirect's case is more serious, so it also carries a red integrity-warning tag on its vendor page and on every downgraded listing's note.
Until reports are individually re-confirmed one by one, treat "Verified COA" as meaning a specific named-lab report is linked for that listing — not that we've visually checked its Client field matches the vendor. Always click through and check the report yourself, including who it was issued to, before relying on it.
How "Best value (verified)" is decided
The best-value badge is only ever awarded among listings with a confirmed size (in mg) and a Verified COA. A cheaper, unverified listing is still shown — we don't hide it, since price is real information — but it will never carry the best-value badge, even if it's the lowest number on the page. This is meant to stop the cheapest, least-documented listing from looking like the "winning" option by default.
Code names and aliases
A few vendors sell a peptide under a code name rather than its common name — most notably Cellpept, which lists Retatrutide as "GLP3-R" and Tirzepatide as "GLP2" (likely to avoid using the actual drug names directly). We track these under their common name and note the alias on the listing, and searching either name finds the same result.
Independence
PeptideCompare has no ownership stake in, and no business relationship with, any vendor listed on this site. Every vendor is scored against the same three verification tiers described above, with no exceptions.
Affiliate links
Some "Visit site" links on this site may in the future be affiliate links, meaning we could earn a commission if you make a purchase after clicking through — at no extra cost to you. This never affects a listing's price, size, or verification tier, all of which are recorded the same way regardless of any commercial relationship. Any vendor with an active affiliate arrangement will be marked as such.
Scope and limits
We focus on vendors that ship within Europe and currently track 46 research peptides and related products. This is a manually maintained snapshot, not an exhaustive market survey — some vendors we found couldn't be reached or verified and aren't listed yet. Everything here is for research purposes; nothing on this site is medical advice, and we don't make dosing or usage recommendations.