Key Takeaways
- We score vendors on three factors: price (40%), COA documentation (30%), and reputation (30%)
- Nura Peptide is our top-ranked pick — published COAs on a testing process the vendor walked us through, GLP-1 compounds through copper-peptide skincare in one catalog, and an active coupon code
- Ascension Peptides offers the deepest standing discount — 50% off automatically through our link
- Multiple vendors shut down in 2025-2026 — the surviving vendors are stronger for it
- Every vendor listed has a floor score of 8.0 — if they're on this list, they're worth buying from
We score every vendor on three things that actually matter: price, COA testing, and reputation. Beyond the score, we give an edge to vendors whose process we've reviewed in detail and trust — when a vendor has walked us through its testing first-hand, that earns weight the raw numbers can't capture. Rankings change as the data and our diligence do.
The Peptide Catalog earns a commission when you buy through the vendor links on this page, at no extra cost to you.
Here's how we rank vendors, who makes the cut in 2026, and who to avoid.
How We Score Vendors
Every vendor on this list is evaluated using the same formula:
Score = Price (40%) + COA Documentation (30%) + Reputation (30%)
| Factor | Weight | What We Measure |
|---|---|---|
| Price | 40% | Normalized 8-10 against best/worst price per peptide |
| COA | 30% | Third-party Certificate of Analysis availability (has COA = 10, none = 8.0) |
| Reputation | 30% | Track record, community feedback, shipping consistency |
Floor score: 8.0. If a vendor is listed here, they've cleared a quality threshold. We don't list bad vendors and then warn you about them — we just don't list them.
We score whether a vendor publishes third-party COAs; we don't independently re-test each certificate unless we say so. A COA's presence is a documentation signal, not a purity guarantee.
Scores are updated continuously based on real pricing data from our price comparison tool and ongoing quality monitoring.
The Vendor Landscape in 2026
The research peptide market looks fundamentally different than it did 18 months ago.
Multiple major vendors shut down between mid-2025 and early 2026: Peptide Sciences (March 2026), Amino Asylum (FDA raid, June 2025), Paradigm Peptides (founder sentenced to 70 months in prison, July 2026), and Science.bio (January 2026).
The closures were driven by three forces:
- FDA enforcement accelerated — warning letters, warehouse raids, and criminal prosecutions
- Pharmaceutical companies filed lawsuits — Eli Lilly and Novo Nordisk targeted GLP-1 suppliers
- Quality failures were exposed — third-party testing revealed inconsistencies at some major vendors
The silver lining: the vendors that survived are the ones that invested in quality, compliance, and transparency. The bar for operating a peptide vendor has never been higher — and that's good for buyers.
