Independent side-by-side comparison of Modern Peptides and ZLZ Peptide — third-party lab grades, tested purity, COA availability, FDA warnings, and community ratings.
Bottom line: ZLZ Peptide holds the stronger independent lab grade (ungraded vs C); Modern Peptides shows higher average tested purity (99.7% vs 99.2%); Modern Peptides has more published third-party tests (25 vs 9).
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.
Modern Peptides: 25 independent Janoshik assays, across 20 substances, median measured purity 99.8%, most recent 2026-02-24. ZLZ Peptide: 9 independent Janoshik assays, across 9 substances, median measured purity 99.7%, most recent 2025-11-20.
| Attribute | Modern Peptides | ZLZ Peptide |
|---|---|---|
| Independent lab grade | Not graded | C |
| Third-party tests | 25 tests, avg purity 99.7% | 9 tests, avg purity 99.2% |
| COA available | No | No |
| Endotoxin tested | No | No |
| FDA warnings | None on record | None on record |
| Substance | Modern Peptides | ZLZ Peptide |
|---|---|---|
| Tirzepatide 30mg | 99.85% (1 assay, latest 2026-01-26) | 99.84% (1 assay, latest 2025-03-06) |
| Retatrutide 10mg | 99.74% (2 assays, latest 2026-01-26) | 99.69% (1 assay, latest 2025-03-06) |
| Semaglutide 10mg | 99.69% (1 assay, latest 2025-12-15) | 99.74% (1 assay, latest 2024-11-29) |
| Retatrutide 20mg | 99.80% (3 assays, latest 2026-02-24) | Not tested |
| Tirzepatide 15mg | 99.78% (2 assays, latest 2026-01-16) | Not tested |
| Tesamorelin 20mg | 99.75% (2 assays, latest 2026-01-09) | Not tested |
| Retatrutide 50mg | 99.92% (1 assay, latest 2026-02-24) | Not tested |
| KLOW 80 | purity not reported (1 assay, latest 2026-02-23) | Not tested |
| Cartalax 20mg | 99.71% (1 assay, latest 2026-01-16) | Not tested |
| Bpc-157 20mg | 99.50% (1 assay, latest 2026-01-16) | Not tested |
| GLOW 70 (bpc-157, Tb500, Ghk-cu) | purity not reported (1 assay, latest 2025-12-15) | Not tested |
| Bpc-157/tb500 10mg/10mg | purity not reported (1 assay, latest 2025-10-15) | Not tested |
| Checked | Modern Peptides | ZLZ Peptide |
|---|---|---|
| Certificates of analysis | 1 published on the site | Not stated |
| Products listed | 75 | Not stated |
| Public pricing | Listed on the site | Not stated |
| Payment methods | Cryptocurrency, Bank Transfer, Credit Card | Not stated |
| Ships to | United States, United Kingdom, Canada, Worldwide | Not stated |
| Carriers | FedEx, UPS, USPS, Canada Post | Not stated |
| Research-use-only notice | Published | Not stated |
Modern Peptides. Modern Peptides: 25 independent Janoshik assays, across 20 substances, median measured purity 99.8%, most recent 2026-02-24. ZLZ Peptide: 9 independent Janoshik assays, across 9 substances, median measured purity 99.7%, most recent 2025-11-20. These are third-party Janoshik assays published against the vendor, not the vendor's own certificates.
Tirzepatide 30mg has been independently assayed for both. Modern Peptides measured a median 99.85% across 1 assay; ZLZ Peptide measured 99.84% across 1. Purity reflects the lots actually tested, not every batch either vendor sells.
Modern Peptides publishes 1 certificate of analysis on its own site, and we have not read ZLZ Peptide's site. A published COA is the vendor's own document; the assay figures elsewhere on this page are independent of it.
Modern Peptides states it ships to United States, United Kingdom, Canada, Worldwide, and ZLZ Peptide does not state one. Both are read from the vendors' own sites.
Full profiles: Modern Peptides, ZLZ Peptide.
Full lab-test records: All 25 Modern Peptides lab tests, All 9 ZLZ Peptide lab tests.
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