The State of Peptide Vendor Testing
We audited every one of the 100 US research-peptide vendors we track: their third-party lab testing, COA verification, purity, and pricing. Two findings stand out: only 68% have testing we could independently verify, and the same peptide’s price per milligram varies up to 30× depending on where you buy it.
- US vendors audited
- 100
US vendors audited
- Third-party verified
- 68%
Third-party verified
- Listings with a COA
- 77%
Listings with a COA
- Max price spread
- 30×
Max price spread
Key findings
The transparency gap
“Third-party tested” is the industry’s favorite phrase and its least verified. Of the 100 vendors we audited, 68 clear our testing gate: at least half of their scored products have a certificate whose key we confirmed at the issuing laboratory, a laboratory in our directory that is not tier D. The rest fall below that line; several of them still have many confirmed certificates, just not for half of their products.
Where a vendor’s third-party testing cannot be independently verified, our formula applies a testing gate: the score is held under a cap that starts at 6.0 and rises by at most 2.5 points for operating history, shipping and reviews. See the methodology.
The price lottery: same peptide, wildly different price
For the peptides carried by the most vendors, we compared the lowest per-mg price we recorded with the highest. For the same compound, the two differ by up to 30×. This study compares price only; it does not test whether a higher price tracks product quality.
| Peptide | Vendors | Cheapest $/mg | Priciest $/mg | Spread |
|---|---|---|---|---|
| BPC-157 | 92 | $0.95 | $28.12 | 29.6× |
| TB-500 | 86 | $1.96 | $33.50 | 17.1× |
| Tesamorelin | 86 | $2.33 | $31.80 | 13.6× |
| Ipamorelin | 78 | $1.00 | $28.12 | 28.1× |
| Selank | 77 | $0.92 | $15.00 | 16.3× |
| Semax | 76 | $0.84 | $19.80 | 23.6× |
| Melanotan-2 | 75 | $0.67 | $14.00 | 20.9× |
| PT-141 | 67 | $0.89 | $14.00 | 15.7× |
Prices are the lowest recorded per-mg listing per vendor at audit time. Compare live pricing on each peptide’s page.
Which labs the industry actually uses
Across every COA in our dataset, a handful of independent labs do most of the testing. These are the names that show up most often on verifiable certificates.
Purity: mostly high, but read the COA
Across 1712 certificates with a reported purity figure, the median is 99.68%, reassuringly high. But 103tested below 99%, a reminder that “has a COA” is not the same as “passed.” 93% of vendors publish at least one COA; the number that publish one for everyproduct is far smaller. Always match the certificate to the batch you’re buying.
Methodology
Every figure on this page is computed directly from the Peptide Source Review audit dataset (100 US vendors and 2387product listings) and updates as the data does. A vendor counts as “verified” (it clears the testing gate, rule A9) when at least half of its scored products have a certificate whose key we confirmed at the issuing laboratory, a laboratory in our directory that is not tier D, on a certificate that is not self-issued; vendor claims alone do not count. Prices are the lowest per-milligram figure publicly listed per vendor at audit time. Our full scoring formula and integrity policy are public and applied identically to every vendor, regardless of any affiliate relationship.
Citing this research? Please link to peptidesourcereview.info/research/vendor-testing-2026. Media & data requests: peptidesourcereview [at] gmail.com.