Independent side-by-side comparison of Certified Peptides and Zztai Peptide — third-party lab grades, tested purity, COA availability, FDA warnings, and community ratings.
Bottom line: Zztai Peptide holds the stronger independent lab grade (ungraded vs C); Zztai Peptide 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. Zztai Peptide: 18 independent Janoshik assays, across 17 substances, median measured purity 99.5%, most recent 2025-12-19.
| Attribute | Certified Peptides | Zztai Peptide |
|---|---|---|
| Independent lab grade | Not graded | C |
| Third-party tests | 4 tests, avg purity 99.3% | 18 tests, avg purity 99.3% |
| COA available | No | No |
| Endotoxin tested | No | No |
| FDA warnings | None on record | None on record |
| Substance | Certified Peptides | Zztai Peptide |
|---|---|---|
| Retatrutide 5mg | 99.70% (1 assay, latest 2026-04-01) | 99.24% (1 assay, latest 2025-10-21) |
| Retatrutide 20mg | Not tested | 99.55% (2 assays, latest 2025-12-18) |
| 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 |
| DSIP 5mg | Not tested | 99.01% (1 assay, latest 2025-12-19) |
| Tirzepatide 60mg | Not tested | 99.95% (1 assay, latest 2025-12-18) |
| HGH 191AA (somatropin) 151U | Not tested | 97.83% (1 assay, latest 2025-12-18) |
| Mots-c 10mg | Not tested | 99.10% (1 assay, latest 2025-10-21) |
| Retatrutide 30mg | Not tested | 99.62% (1 assay, latest 2025-10-21) |
| Retatrutide 15mg | Not tested | 99.41% (1 assay, latest 2025-10-21) |
| Retatrutide 50mg | Not tested | 99.69% (1 assay, latest 2025-10-21) |
| Checked | Certified Peptides | Zztai Peptide |
|---|---|---|
| Certificates of analysis | Not stated | None found on the site |
| Products listed | Not stated | 62 |
| Public pricing | Not stated | Listed on the site |
| Payment methods | Not stated | Credit Card, PayPal |
| Ships to | Not stated | United States, United Kingdom, Canada, Australia, New Zealand |
| Carriers | Not stated | DHL, FedEx, UPS, USPS |
| Stated origin | Not stated | Hong Kong |
Zztai Peptide. Certified Peptides: 4 independent Janoshik assays, across 4 substances, median measured purity 99.7%, most recent 2026-04-01. Zztai Peptide: 18 independent Janoshik assays, across 17 substances, median measured purity 99.5%, most recent 2025-12-19. These are third-party Janoshik assays published against the vendor, not the vendor's own certificates.
Retatrutide 5mg has been independently assayed for both. Certified Peptides measured a median 99.70% across 1 assay; Zztai Peptide measured 99.24% across 1. Purity reflects the lots actually tested, not every batch either vendor sells.
We have not read Certified Peptides' site, and we found no certificates of analysis anywhere on Zztai Peptide's site. A published COA is the vendor's own document; the assay figures elsewhere on this page are independent of it.
Certified Peptides does not state a shipping region, and Zztai Peptide states it ships to United States, United Kingdom, Canada, Australia, New Zealand. Both are read from the vendors' own sites.
Full profiles: Certified Peptides, Zztai Peptide.
Full lab-test records: All 4 Certified Peptides lab tests, All 18 Zztai Peptide lab tests.
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