Semax is a synthetic peptide developed from a fragment of ACTH, studied in neuroprotection and cognition research. Like Selank it is a Russian-origin research peptide whose short sequence makes independent identity testing worthwhile. Whatever you pay, the only way to know a vial actually contains Semax at the stated purity is an independent certificate of analysis you can verify, because purity and identity cannot be judged by eye.
Ignore the marketing. The question is simple: does the seller publish a verifiable Janoshik certificate that names the seller itself as the client? If it does, you can confirm an independent lab tested that batch. If it shows an in-house document, a borrowed certificate, or "COA on request", you cannot. Learn the two-minute check in how to verify a Janoshik COA.
Of the 173 active UK research-peptide sellers we audit, only 20 (12%) publish their own verifiable Janoshik certificate. Any of them is where you can actually verify testing, for Semax or any compound. A few: Lab77Peptides · Velonix Labs · Biohacklondon · Peptifyuk · Biohackpeptides · Peptideprime. See the full independently-tested list, or check a specific shop's certificate with the free COA Checker.
An honest note: a verifiable certificate proves a sample of a batch was tested, not that the specific vial you receive matches it, see what this can and can't tell you. The Peptide Watch sells no Semax and links to no shop; this is research-use-only information, not medical or dosing advice.
Other compounds: BPC-157 · TB-500 · GHK-Cu · Ipamorelin · CJC-1295 · MOTS-c · Epithalon · Selank