GLP-1 Research Peptide Vendors 2026: Who Actually Documents Retatrutide, Tirzepatide and Semaglutide

Only three vendors carry all three compounds, and two of them sell them under code names. Real Peptides, Core Peptides, Cenexa Labs, Limitless Life Nootropics and Ascension Peptides listed none of the three under a name they tie to the compound. Ascension sells products named R-10, T-10 and S-5 without stating what they contain, so we did not count them. Real Peptides carries newer incretin compounds instead (cagrilintide, mazdutide, survodutide), which we do not yet cover.

Code names are the first thing to check. “GLP-3”, “RT-3” or “GLP-III” are not chemical names. In each case above, the vendor’s own description, sequence or certificate identifies retatrutide, but a buyer who reads only the product title has no way to know that.

CertaPeptides has the most complete retatrutide documentation: a separate Janoshik report for each vial size from 5 to 50 mg, each with a batch number, and the report keys resolve on Janoshik’s own portal. The vendor also prints its own warning next to reports where the vial was over- or underfilled, ranging from 96.1 percent of label (10 mg, #233668) to 114.8 percent (20 mg, #233674). It does not sell tirzepatide or semaglutide.

Particle Peptides publishes the single most thorough certificate in this set. The Liquilabs report for batch 2026349 names the sample as retatrutide 10 mg and gives 10.14 mg with a stated uncertainty, purity above 99.8 percent, a molecular ion of 4731 Da that matches retatrutide, endotoxin at 0.016 EU/mg and zero microbial counts. The caveats: all results come from one laboratory, and the product is sold as “GLP-3”.

Avellon Peptides is the only vendor whose retatrutide was identified by a blind test. Two Janoshik reports commissioned by the directory ChemVerify screened for semaglutide, tirzepatide and retatrutide without being told which to expect, and found retatrutide at 99.57 and 99.71 percent. The batch field is blank or “Unknown” on both, so the result cannot be matched to the vial a customer receives, and the two vials held 9 and 13 percent more than the label.

Onyx Peptides is the only EU vendor that stocks all three compounds, and it publishes no certificate for any of them. Reports are available on request. That is why Onyx appears as the top audited vendor on our tirzepatide and semaglutide guides: among the vendors that stock those two compounds it has the highest rating, but the rating reflects its general practice, not a document we have seen for these products.

Purified Peptide shows both the best and the worst paperwork in the set. Its tirzepatide certificate (lot TR102026A, 99.74 percent, 10.28 mg, LC-MS identity) resolves at Freedom Diagnostics. Its semaglutide page, however, links a GHK-Cu certificate instead of a semaglutide report, and its retatrutide certificate carries lot RETA6111525N, the same lot number printed on the vendor’s DSIP certificate. Two products cannot share one lot, so at least one of those documents is mislabelled. Purified ships within the US only.

Peptides EU names all three compounds plainly and shows Janoshik results on each page, but the images are cropped “Manufacturer’s Reports”: the client, sample description and batch are cut off, so the result proves that some sample was tested, not that it came from what the shop sells. The operator is not named and the only address is in the United Kingdom.