The best UK research-peptide vendors: independently tested

Of the 173 active UK research-peptide retailers we audit, only 20 (12%) publish their own verifiable Janoshik certificate of analysis, a report that names the vendor itself as the client and can be checked on Janoshik's own website. Ranked below by most recent certificate.

What "best" means here: this is not an endorsement, and we take no payment from any vendor. It is the list of sellers whose testing you can actually verify. Everything else is on the watch list. And remember, even a verifiable COA proves a sample was tested, not that your vial matches it, see what this can and can't tell you.

New to reading certificates? Start with how to verify a Janoshik COA, or upload one to the COA Checker.