How Peptilyze compares prices

Peptilyze does not sell anything and holds no stock. It reads what shops publish, puts it in one format and lets you sort it. This guide follows one product from a shop’s feed to a row in a table, and says where the process stops.

1. Where the data comes from

Every hour we read the public product feed of each tracked shop. For WooCommerce shops that is the Store API the storefront itself uses. A few shops run their own platform, and we read the JSON endpoint their storefront calls. Nothing is typed in by hand, and rendered pages are not scraped.

Our sync introduces itself with a user agent that points to the crawler section of the method page. It makes one series of requests per shop per hour. If a shop blocks us, we do not try to get around it.

2. Matching a product to a compound

Shops name the same compound in different ways, in different languages, and sometimes with a code name. We keep a dictionary of compounds with their known aliases. A product is matched when its name, variant label or slug points to exactly one compound.

• Several compounds in one name (a bundle or a kit) means no match, so bundles never leak into single-compound tables. A blend counts only when the dictionary defines it as a blend.
• Code names are matched only where the shop’s own text confirms them, or, rarely, where we inferred the match from an identical twin listing. Inferred matches carry a “code name” tag.
• Everything else stays out: prescription drugs, supplies, hardware and anything the dictionary does not know.

3. Form, strength and pack size

From the same text we read the form (vial, powder, pen, cartridge, oral, nasal spray or topical), the strength per unit and the number of units in the pack. A comparable product, called a spec, is one compound in one form at one strength: for example “a vial of 10 mg”. Offers are only compared inside a spec.

The arithmetic is explained in the price per mg guide.

4. One price basis

Every price is shown in euros including VAT. Shops that list prices without VAT get a rate added, and those rows are marked. Shipping is not part of the price. Details are in the VAT and shipping guide.

5. Which offer is “lowest”

• Only offers in stock can be the lowest. Sold-out offers stay visible and greyed out.
• Cross-shop comparison uses single units. Packs are compared per unit and can get a “Best per unit” hint.
• The order in a table is: in stock first, singles before packs, then cheapest per unit.

There is no paid placement. Order is decided by price and stock. Links to shops are marked nofollow sponsored as a precaution.

6. Spread and price index

The spread of a spec is how far the dearest shop is above the cheapest, measured on in-stock single units, and needs at least two shops.

The price index of a shop is the mean of its own price divided by the lowest price, taken over every spec that at least two shops sell in stock. An index of 1.00 means always the cheapest. It appears only once a shop shares at least three specs with others, and with few shops it is a rough guide.

7. Freshness and failures

Each hourly run is stored with its time. If a shop fails to respond, or returns less than half of what it listed before, we keep its earlier prices, mark the shop as stale and say so on the page. One failing feed never empties the site.

What we do not check

A listing on Peptilyze is not an endorsement of the shop or the product. We do not verify:

• what is actually in a vial, or its purity;
• laboratory reports, which are the seller’s own documents (see the certificate of analysis guide);
• shipping times, shipping costs, customer service or company registration;
• whether a shop’s stated VAT status is right.

Prices and stock can change between our last sync and your visit. Check the shop’s own page before you order.