Ascension Peptides is the more transparent vendor of the two, as of September 2026. Its COA library can be searched by batch/lot and has been traced to a named lab, MZ Biolabs. For Core Peptides' COA images, we couldn't identify the lab or tie them to a lot. Core has two advantages: its product names say what the product is, and it has a small amount of independent Finnrick data. Ascension has neither.
Notice: Both vendors sell products for laboratory research only. They are not FDA-approved and not for human or animal consumption. This comparison covers supplier transparency only, based on public documentation. We didn't purchase or test products.
Side-by-side
| Ascension Peptides | Core Peptides | |
|---|---|---|
| Our score | 6.4 | 5.0 |
| COA format | Searchable library (85 records) by product, SKU, batch/lot, purity, date | COA images on product pages |
| Testing lab | MZ Biolabs (identified by two independent reviews) | Not disclosed / not verifiable |
| Lot traceability | Yes (batch/lot search) | Not confirmed |
| Finnrick data | None published | 3 tests, 75%, 1 of 3 passed (GLP-1-class only) |
| Product naming | Some items listed only as codes (C-10, R-10, S-5, T-30…) | Compounds named |
| Research-use labeling | RUO, 21+, not for human consumption | RUO, "Human/Animal Consumption Prohibited" |
| Shipping | US only | US; free over $200 |
| Payment | Not verified | Mastercard shown |
| Ownership / address | Anonymous; conflicting addresses reported | No address found |
| FDA warning letter | None found | None found |
Sources: Ascension COA page, Ascension shop, Project Biohacking on Ascension, Peptide Grades on Ascension, Core Peptides homepage, Core BPC-157 page, Finnrick pages for Ascension and Core.
COA transparency
This is where the gap between the two is largest.
Ascension runs a dedicated COA database with 85 records, filterable by batch/lot, cap color, purity and date. Two independent reviewers, Project Biohacking and Peptide Grades, identify the lab as MZ Biolabs in Tucson, Arizona, testing by HPLC-UV-MS. Oddly, the COA page itself doesn't name the lab.
Core Peptides shows certificate images on product pages. The BPC-157 page, for example, has separate images for the 5mg and 10mg sizes. We couldn't read a lab name or lot number from the page content, and the site's /coa/ path returned a 404 when we checked.
Edge: Ascension, clearly. A certificate you can match to your lot and trace to a lab can be checked. One that you can't do either with has to be taken on trust. See how to read a peptide COA.
Independent testing
Neither vendor has much independent data. Finnrick has three Core Peptides tests. All were on GLP-1-class compounds, which we don't cover, and one passed. Ascension has no Finnrick tests. Neither dataset says anything meaningful about the rest of either catalog. More on this in Janoshik vs Finnrick.
Edge: Slightly Core, though only because Ascension has no data at all.
Labeling and product naming
Both use strict research-use-only language. The difference is naming. Several items in Ascension's shop appear only as short codes, such as C-10, R-10, R-30, S-5, T-10 and T-30, without naming the compound. The FDA's August 2026 letter to Peptide Partners identified similarly abbreviated product names as GLP-1-class drugs. Core Peptides names its compounds. We treat code-named products as a transparency negative and don't cover GLP-1-class products at all. Background: FDA peptide regulation in 2026.
Edge: Core.
Business transparency
Neither is strong here. Third-party reviewers report that Ascension has anonymous ownership, two different addresses and Nevis governing law in its terms. It does publish a Colorado phone number. We found no street address for Core Peptides on the pages we reviewed.
Edge: Even. Both are weak.
What each would need to close the gap
Ascension is the closer of the two to our top tier. It would need to name its lab on its own COA page, replace code-named listings with compound names, and get some independent Finnrick results. With those, its documentation would be comparable to Peptidology's.
Core Peptides has further to go. Its labeling is already clean, but it would need to name the lab behind its certificates, link each COA to a lot number, and publish them in one searchable place. Independent tests across more than one compound class would also help.
Checking either vendor yourself
Whichever you look at, the same checks apply:
- Find the certificate for the exact lot on your vial.
- Confirm the lab name and contact the lab to verify the report.
- Check that the COA includes identity (mass spec) as well as purity.
- Look up the vendor on Finnrick and in FDA's warning letter database.
Bottom line
Ascension's lot-searchable, lab-traceable COA library is the deciding factor. That's the one piece of evidence you can check yourself, and Core doesn't offer an equivalent we could verify. Ascension would score higher still if it named its lab on its own site, dropped the code names and got some independent test data.
Full reviews: Ascension Peptides review · Core Peptides review
Visit Ascension Peptides · Visit Core Peptides
Other comparisons: Peptidology vs Limitless Biotech · Full rankings: best peptide vendors