Peptide.Promo is a price comparison platform designed for researchers who purchase research peptides. Its primary function is to aggregate and normalize pricing data from multiple vendors, converting all listed prices into a cost per milligram (price per mg) metric. This approach allows users to compare the actual cost of peptides across different suppliers, moving beyond simple sticker prices to identify the most cost effective source for a given compound. The platform tracks over 1,785 live prices across a range of popular peptides and vendors. It features a searchable database organized by peptide category, individual compound, and vendor. Users can browse popular peptides such as those from Pure Bio Labs, NG Peptides, Puratek, Behemoth Labz, and others, with each vendor listing showing the number of current offers. Sponsored placements are clearly labeled to distinguish them from organic results. The tool also includes current promo codes from various vendors. Typical use cases involve a researcher selecting a specific peptide, viewing a side by side comparison of prices from different vendors sorted by real price per mg, and then identifying the cheapest source. The workflow is straightforward: a user navigates to the site, selects a peptide or browses by category, reviews the normalized pricing data, and optionally applies a promo code from the listed vendors. The platform does not sell peptides itself but serves as a data aggregation and comparison tool. Technically, the site functions as a web based directory and price tracker. It requires no installation or account creation to view prices. The data is updated regularly to reflect current vendor listings. The platform covers a wide range of payment methods accepted by vendors and provides frequently asked questions to assist new users in understanding the price per mg comparison methodology.