How we score.

We score every supplier on five criteria. Weights reflect how often each criterion actually breaks for buyers — not what's easiest to evaluate.

Purity data transparency (30%)

Does the supplier publish HPLC chromatograms — not just purity percentages? Are mass-spec results attached? Is the testing wavelength disclosed? A ">99% pure" claim with no underlying chromatogram is roughly worthless.

Certificate of Analysis per lot (25%)

The COA must be lot-specific. A single reused COA across multiple batches scores zero in this category. Bonus for COAs that include counter-ion identity, peptide content (vs gross mass), and endotoxin/bioburden figures.

Shipping practices (15%)

Cold-chain packaging where the peptide warrants it. Ship times under 7 days domestic. Reasonable international policy. Discreet packaging where customers prefer it.

Customer support (15%)

Email response under 24 hours. Live chat or phone if reachable. Response quality measured by whether they can answer technical questions about COA fields without escalating.

Refund policy (15%)

Clear, written refund policy on the site. Reasonable window. Honored without friction when invoked. Suppliers with no published policy score below 5.

What we don't score

• "Brand reputation" — too gameable
• Anecdotal customer reviews on third-party sites
• Social media presence
• Marketing aesthetics

Conflict of interest

Vial Verdict earns affiliate commissions when readers purchase through some supplier links. We disclose affiliate status on every review. Scores are not adjustable by suppliers — paid or otherwise.