What does 'third party tested' actually mean for a peptide seller?

It should mean an independent laboratory, not the seller itself, measured the vial's purity and dose and published a report. In practice the phrase is used loosely: our review of the market's own certificates found a spread from linked-lab reports (a named, checkable laboratory) down to claim-only pages with no certificate at all. Ask which laboratory, ask for the report number, and check whether that lab has a portal where the report can be verified independently of the seller.

Educational use only. This database summarizes published research and is not medical advice. Where a dose appears it is a record of what a trial or clinic ran, or what people describe doing, with its source attached. Nothing here is a recommendation for personal use.

Part of buying, vendors, and lab testing. How to evaluate a seller's claims, certificates of analysis, and pricing.