A peptide is simply a short chain of amino acids — what differs between classes is which receptors or pathways they're studied against. This page is a map of that landscape, not a guide to using any specific compound.
Research peptides are grouped less by their chemistry and more by the biological system they're studied in relation to. A fifteen-amino-acid chain and a thirty-amino-acid chain can belong to the same research category if they're both investigated against, say, the growth hormone axis — while two peptides of near-identical length can fall into entirely different categories if one is studied for tissue repair and the other for metabolic signaling.
The categories below are the ones most commonly used in the research literature and by compound suppliers to organize their catalogs. They're a starting point for navigating the field, not a clinical classification system.
This class is studied for its interaction with the ghrelin receptor and downstream effects on the growth hormone axis. It includes growth hormone releasing peptides (GHRPs) and growth hormone releasing hormone (GHRH) analogs, which are often studied together in the literature for their combined effect on pulsatile GH release in animal models.
A broad category covering peptides studied for their role in angiogenesis, wound healing, and gastrointestinal protection in preclinical models. BPC-157 is the most widely referenced compound in this category — see its library entry for more detail.
This category includes GLP-1 receptor agonists and related incretin-mimetic compounds, which are extensively studied in metabolic research for their effects on glucose regulation and satiety signaling. Several compounds in this class have also been developed into approved pharmaceuticals — the research-grade versions referenced in academic literature are chemically distinct from, and not interchangeable with, any approved drug product.
A smaller, less standardized category covering compounds studied for their proposed roles in telomerase activity, mitochondrial function, or cellular senescence. The evidence base here tends to be earlier-stage — mostly in-vitro or short-duration animal studies — so this category warrants the most caution when evaluating claims.
A note on evidence quality. Almost everything referenced on this site describes preclinical research — in-vitro studies or animal models — rather than human clinical trials. That distinction matters: a mechanism observed in a petri dish or a rodent model does not establish safety or efficacy in humans. Treat any claim that skips over this distinction with skepticism.