Directory method
Listings are alphabetical and unpaid. We record public website information, not private test results or customer experience. No company has reviewed or approved this page. A listing is not an endorsement. Last checked: 19 September 2026.
The comparison criteria
For every company, look for the same evidence: a batch-specific COA; separate identity and purity methods; a traceable laboratory and report number; a label-to-report batch match; accessible contact and policy information; precise storage and dispatch statements; and careful research-only wording. A supplier can change its website or evidence at any time, so readers should repeat these checks.
Companies readers may encounter
Astra Labs
Publishes UK research-peptide information and product pages. Check the current batch page for the report type, laboratory and matching identifier.
Visit Astra Labsexternal · official website
BluePeak
Its website states that certificates are available by lot and refers to independent testing. Verify the actual report and lot match rather than relying on the general statement.
Visit BluePeakexternal · official website
Core Peptides UK
Its website discusses batch records and COA availability. Check whether identity and purity methods, dates and batch identifiers are visible for the item being considered.
Visit Core Peptides UKexternal · official website
Midshire Labs
Formerly branded Regen Peptides. Its website states that materials are independently tested for identity, purity and mass. Confirm the evidence attached to the current batch.
Visit Midshire Labsexternal · official website
PepSource
Its website describes independently tested purity and COA verification. Review the underlying report, issuer and matching batch code.
Visit PepSourceexternal · official website
ResearchPeptide.co.uk
Its website states that every batch has a COA. Readers should distinguish a downloadable document from independent confirmation that the supplied batch matches it.
Visit ResearchPeptide.co.ukexternal · official website
ZENTRA Peptides
Its website publishes testing, batch-traceability and UK research-peptide information. Check the current batch documentation and the scope of each analytical method.
Visit ZENTRA Peptidesexternal · official website
How to interpret the directory
A supplier’s own statement is a lead to inspect, not independent proof. “Third-party tested” should prompt four questions: which laboratory, which method, which report and which batch? “99% purity” should prompt questions about peak integration, identity confirmation and net peptide content. Our COA guide explains each field.
We do not reproduce review-platform scores because scores change, can reflect delivery rather than analytical quality, and require a clear date and methodology to be meaningful. We also do not use supplier logos, promotional copy or superlative labels such as “best”.
Corrections and inclusion
Companies may send a correction with a public source through our editorial contact form. Corrections do not guarantee favourable wording or inclusion. We may add or remove listings when public information changes, using the same criteria for all companies.
Frequently asked questions
Is this a ranking of the best UK peptide companies?
No. Companies are listed alphabetically. Inclusion means the company has a relevant public UK website, not that its products or claims have been independently approved by this publication.
Does a COA prove a peptide is safe?
No. A COA reports specified analytical results for a sample. It does not by itself establish safety, sterility, suitability for a particular use or regulatory approval.
What is the most important supplier check?
The evidence must connect to the exact batch supplied. A polished report for an unidentified or different batch has limited value.