Methodology
How we vet vendors
Every vendor on our Recommended Sources list is scored against the same public criteria. The scoring is identical for affiliated and non-affiliated vendors — affiliation never changes a grade.
Advertising disclosure: Some links on this site are affiliate links. If you click one and make a purchase, we may earn a commission at no additional cost to you. Affiliate relationships never affect our vetting criteria or scores, which are applied equally to every vendor.
- 01
Per-batch COA
A certificate of analysis is published for each batch, not a single static document reused across products.
- 02
Independent lab
Testing is performed by an independent, accredited laboratory rather than self-reported in-house numbers only.
- 03
Purity (HPLC)
Purity is demonstrated by HPLC with a visible chromatogram, not just a quoted percentage.
- 04
Identity confirmation
Molecular identity is confirmed by mass spectrometry or an equivalent orthogonal method.
- 05
Transparency
Documentation, lab attribution, and batch references are easy to find and verify before purchase.
- 06
Consistency
Quality holds across batches and over time, evidenced by a track record of documentation.
How scoring works
Each criterion is scored from 0–10 based on publicly verifiable documentation. We publish the per-criterion scores and notes so you can check our reasoning against the source documents yourself. Scores are reviewed as vendors publish new batches; recommendations are presented as a scored, multi-vendor comparison, never a single-vendor billboard.