Buyer's guide
Our picks for research peptide vendors in October 2026 are American Peptides, NextGenPeps, PSPeptides, Blank Peptides, Ascension Peptides, Peptide Plugs, Peptide Confidential, Swiss Chems, Licensed Peptides and Alpha Pro Peptides. American Peptides is our #1 pick (9.1/10) for its lot-number COA lookup, followed by NextGenPeps (8.8/10), which names its labs on every COA. Prices for popular peptides at each vendor are in the shop section above, checked on the vendors' own stores. No vendor here has a strong independent testing record yet, so read every score as "how well documented," not "guaranteed pure."
Notice: Research peptides are sold for in-vitro laboratory research only. They are not FDA-approved, not for human or animal consumption, and nothing on this site is medical advice. We rate supplier transparency, not results or uses.
How this list works
Every vendor gets an overall score out of 10. It starts from our published transparency method, which covers COA publication, lab traceability, independent Finnrick data, labeling, business transparency and FDA record, and it also weighs price, catalog, discount codes, shipping and partnership terms. The order is our editors' pick. Each review also shows the transparency score on its own, so you can compare vendors on documentation alone. Affiliate relationships can affect which vendors we feature, their order and their overall score; they never change what we report about COAs, labs or FDA records.
All ten had live storefronts and public COAs when we checked on September 26, 2026 (September 28 for Licensed Peptides, October 12 for Blank Peptides, October 13 for Peptide Confidential). We don't hide problems to fit the order: one vendor has an FDA warning letter, and another publishes dosing guides. Both are disclosed below and scored in their ratings.
The short version
- American Peptides (9.1/10): our #1 pick. It offers a lot-number lookup with 126 lot-matched certificates and names Bioviridian as its lab on its homepage. It's new (domain registered February 2026), has no independent tests, and uses health-style names such as a "Glow Up Research Stack."
- NextGenPeps (8.8/10): names both labs (Janoshik and BioRegen) on every COA entry and publishes its LLC and San Diego address. It has no Finnrick data, and three GLP-1-class items are sold under codes.
- PSPeptides (8.5/10): dated COAs for about 60 products and a 4.2/5 Trustpilot score. Its blog publishes human dosing guides, and it doesn't name its lab on its site. Our partner code CHECKED gives 10% off at PSPeptides; we may earn a commission if you use it, and it doesn't affect the transparency score.
- Blank Peptides (7.8/10): a purity certificate and a separate endotoxin report for each current lot, from named labs (Horizon Analytical and Freedom Diagnostics), with a lot number on every vial and a lookup page. It's new (domain registered March 2026), names no legal entity and has no independent tests. Our partner code CHECKED gives 10% off the entire order; we may earn a commission if you use it, and it doesn't affect the transparency score.
- Ascension Peptides (8.1/10): an 85-record COA library you can search by batch or lot, with certificates independent reviewers trace to MZ Biolabs. The site names no lab, entity or address, there are no Finnrick tests, and six items are sold under codes. Our partner code AFFILIATE50OFF gives 50% off a first order; we may earn a commission if you use it, and it doesn't affect the transparency score.
- Peptide Plugs (7.5/10): names its lab (Freedom Diagnostics) on its site, with accession codes you can check at the lab, and publishes its LLC and a Liberty Hill, TX address. The domain is from December 2025, there are no Finnrick tests, and its shop uses categories like "Weight Loss" and "Anti-Aging."
- Peptide Confidential (7.6/10): the only vendor here that publishes every lot it has had tested, including 5 rejected and 2 withdrawn, with the lab (Peptide Test Canada or Testides) named on each record and a lookup code on every vial. It's a family business in Calgary, Canada: new (domain registered July 2026), no legal entity, no independent tests, and US orders clear customs and are charged in Canadian dollars.
- Swiss Chems (6.5/10): has operated since 2018 and is the only one of the ten with Finnrick data, but that's 48% with 4 of 10 passing. It received an FDA warning letter in December 2024.
- Licensed Peptides (7.4/10): names two accredited labs (Vanguard Laboratory and Ethos Analytics) on its site, publishes endotoxin reports, and gives a legal entity and a Boca Raton, FL address. Some reports appear to reuse lot numbers across products, Trustpilot removed its profile, and GLP-1-class items are sold under codes. Our partner code Affiliate5 gives 5% off; we may earn a commission if you use it, and it doesn't affect the transparency score.
- Alpha Pro Peptides (6.3/10): a COA table with lot ID, date, purity and net content, from Freedom Diagnostics. It's very new, publishes no address, and sells GLP-1-class products under codes.
Head-to-head: American Peptides vs NextGenPeps, Blank Peptides vs NextGenPeps, Blank Peptides vs PSPeptides, Peptide Confidential vs Blank Peptides and Swiss Chems vs PSPeptides.
Ratings at a glance
| Vendor | Overall | Transparency | Lab named | Finnrick | FDA letter |
|---|---|---|---|---|---|
| American Peptides | 9.1 | 7.6 | Homepage only | 0 tests | None found |
| NextGenPeps | 8.8 | 8.0 | Yes, on each COA entry | No profile | None found |
| PSPeptides | 8.5 | 7.0 | On PDF only | 0 tests | None found |
| Blank Peptides | 7.8 | 7.8 | Yes, on site and certificates | No profile | None found |
| Ascension Peptides | 8.1 | 7.4 | Not on site (reviewers: MZ Biolabs) | 0 tests | None found |
| Peptide Plugs | 7.5 | 8.1 | Yes, with lab lookup codes | 0 tests | None found |
| Peptide Confidential | 7.6 | 7.6 | Yes, on every lot record | No profile | None found |
| Swiss Chems | 6.5 | 7.2 | FAQ only | 48%, 10 tests | Dec 2024 |
| Licensed Peptides | 7.4 | 7.4 | Yes, on its reports pages | No profile | None found |
| Alpha Pro Peptides | 6.3 | 7.5 | On PDF only | No profile | None found |
Why a COA alone isn't enough
A COA is a document, and documents can be faked. In July 2026, the owner of Paradigm Peptides was sentenced to 70 months. Prosecutors said the company falsely marketed its products as domestically made and tested. That's why we weight two things a vendor can't easily fake:
- A named lab you can check. Janoshik, Bioviridian, BioRegen, Freedom Diagnostics and Horizon Analytical all run public lookup tools. See how to read a peptide COA.
- Independent samples. Finnrick publishes results from samples customers buy and submit. Nine of these ten vendors have no Finnrick tests yet. See Janoshik vs Finnrick.
What else we checked
Research peptide vendors keep disappearing or getting flagged. Peptide Sciences shut down in March 2026, and FDA sent another round of warning letters on August 24, 2026 (FDA's 2026 peptide letters). For every vendor, we searched FDA's warning letter database. We also read the pages that most often cause trouble: blogs, bundles and FAQs. That's where we found PSPeptides' dosing guides and American Peptides' benefit-style bundle names.
All ten sell GLP-1-class compounds, some under code names (for example "GLP-RT"). We list them like any other research compound: prices and COAs only, with no dosing or human-use content. FDA's position on these compounds is covered in our FDA regulation guide. For the legal basics, see are peptides legal?
For more, see best peptide vendors in the USA, third-party tested peptides and our 10-point checklist for choosing a peptide vendor. GLP-class prices and COAs are compared in retatrutide, tirzepatide and semaglutide vendors.
Free reconstitution calculator
Our free peptide reconstitution calculator turns a vial's mg and the mL of bacteriostatic water added into a concentration (mg/mL) and the volume for a given amount, for research use only.
More free tools: the BAC water calculator, IU to mg calculator and unit converter, COA checklist and our monthly vendor testing tracker. Current discounts are on the peptide coupon codes page, and quick answers are in our FAQ.
A note on risk
Vendor facts are a snapshot from our September 26-October 13, 2026 checks; shop prices were checked October 7, 2026. Vendors in this market can change labs, lose payment processors or shut down within weeks. Before relying on any COA, match the lot number to your vial and verify the certificate with the lab that issued it.
