Independent side-by-side comparison of Certified Peptides and Penguin Peptides — third-party lab grades, tested purity, COA availability, FDA warnings, and community ratings.
Bottom line: Certified Peptides shows higher average tested purity (99.3% vs 99.2%); Penguin Peptides has more published third-party tests (18 vs 4).
Every figure below is either measured by an independent laboratory or read from the vendor's own website, and the source is named against it. PeptideAtlas is not affiliated with either vendor.
Certified Peptides: 4 independent Janoshik assays, across 4 substances, median measured purity 99.7%, most recent 2026-04-01. Penguin Peptides: 18 independent Janoshik assays, across 17 substances, median measured purity 99.8%, most recent 2026-01-22.
| Attribute | Certified Peptides | Penguin Peptides |
|---|---|---|
| Third-party tests | 4 tests, avg purity 99.3% | 18 tests, avg purity 99.2% |
| COA available | No | No |
| Endotoxin tested | No | No |
| FDA warnings | None on record | None on record |
| Substance | Certified Peptides | Penguin Peptides |
|---|---|---|
| GLOW 70mg | Not tested | purity not reported (2 assays, latest 2026-01-21) |
| Retatrutide 5mg | 99.70% (1 assay, latest 2026-04-01) | Not tested |
| Selank 10mg | 99.79% (1 assay, latest 2026-03-31) | Not tested |
| Epitalon 50mg | 98.00% (1 assay, latest 2026-03-31) | Not tested |
| Lpamorelin 10mg | 99.77% (1 assay, latest 2026-03-31) | Not tested |
| HGH 191AA 36iu | Not tested | 96.33% (1 assay, latest 2026-01-22) |
| Glp-1 T 120mg | Not tested | 99.88% (1 assay, latest 2026-01-21) |
| Glp-1 T 60mg | Not tested | 99.86% (1 assay, latest 2026-01-21) |
| Glp-3 R 30mg | Not tested | 99.88% (1 assay, latest 2026-01-21) |
| KLOW 80mg | Not tested | purity not reported (1 assay, latest 2026-01-21) |
| Mots-c 40mg | Not tested | 99.54% (1 assay, latest 2026-01-21) |
| BACTERIOSTATIC WATER 10ml | Not tested | purity not reported (1 assay, latest 2026-01-21) |
Penguin Peptides. Certified Peptides: 4 independent Janoshik assays, across 4 substances, median measured purity 99.7%, most recent 2026-04-01. Penguin Peptides: 18 independent Janoshik assays, across 17 substances, median measured purity 99.8%, most recent 2026-01-22. These are third-party Janoshik assays published against the vendor, not the vendor's own certificates.
Full profiles: Certified Peptides, Penguin Peptides.
Full lab-test records: All 4 Certified Peptides lab tests, All 18 Penguin Peptides lab tests.
Related comparisons: Certified Peptides vs BioTech Peptides, Penguin Peptides vs Apex Peptides, Certified Peptides vs Mei Peptide, Penguin Peptides vs Fenrir Labs Uk LTD, Certified Peptides vs Qingfuji Trading, Penguin Peptides vs Limitless Life Nootropics.