How rankings work

The rating you see

A vendor's rating is the average overall rating (1–5 stars) of its published reviews, next to how many reviews there are and how many are verified purchases. Reviews our moderators hid don't count. Optional ratings for shipping, packaging, support and value are averaged separately from the reviews that include them.

How ratings are compared

A 5.0 from one review shouldn't outrank a 4.8 from forty. When we sort by rating, each average is weighted by its number of reviews:

ranking rating = (5 × m + n × average) ÷ (5 + n)

n is the vendor's number of reviews and m is the average rating across all vendors (4.0 until there are at least 50 reviews site-wide). With few reviews the result stays close to m; with many it approaches the vendor's own average. Vendors without reviews have no ranking rating and sort after rated ones.

Sort options

• Best match (default): when you've chosen a shipping destination, vendors that ship there (fully or to part of it) come first, then vendors whose shipping we haven't confirmed, then those that don't ship there. Within each group, vendors are scored on how well they match your search (50%), ranking rating (20%), how many of the peptides you asked about they list (15%), recent activity (10%) and catalog size (5%). Parts that don't apply, such as search without a query, are left out and the rest reweighted.
• Most popular: visits to the vendor's site from Peptide Library in the last 30 days (counted at most 5 times per vendor per day) plus twice the reviews of the last 30 days, each on a logarithmic scale.
• Highest rated uses the ranking rating; Most reviews, Newest reviews, Most products, Largest discount, Recently added and A–Z do what they say.
• Ties are always broken by name, so the order is the same every time.

Verified purchases

A review shows "Verified purchase" only after our team checks a receipt or order confirmation the reviewer uploaded. Receipts stay private: only the reviewer and our moderators can see them. Photos are public and don't verify a review; reviews verified before October 2026 went through an earlier check. Each account can review a vendor once and edit that review anytime; edited reviews say so. People who manage a vendor's listing can't review it, and anyone can report a review for our moderators to check.

Shipping, coupons and facts

• Where a vendor ships comes from its own shipping policy. A vendor counts as shipping to you only when its policy says so; unconfirmed vendors are never shown as shipping to you.
• Coupon codes, shipping prices, delivery times and return policies are what the vendor states, with the date we checked. Codes are applied at the vendor's checkout, and code prices we show are estimates.
• When a vendor doesn't state something, we show "Not stated" rather than guessing.

What rankings are not

• Not a clinical recommendation, quality or safety rating.
• Not an endorsement for human use.
• Not paid advertising. Some links carry a referral parameter and Peptide Library may earn a commission on qualifying purchases; whether a vendor has a referral link or a coupon never changes its rating or its order.

Prices

Prices are what each vendor's site listed when we last checked, with that date. Price per mg divides the price by the total milligrams in the listing when both are known; different strengths and forms are never compared with each other. When a vendor's code states a percentage off, the price we show is after that code and says "with code", with the vendor's own price crossed out; the vendor's checkout decides whether the code applies. Always confirm the current price on the vendor's site.

Each product card in the Shop shows one vendor's offer: among vendors that ship to you and have it in stock, the one with the highest ranking rating, then the lowest price per unit. Vendors without reviews count at m here, so a poorly reviewed vendor isn't shown ahead of one with no reviews. When you sort the Shop by price, the card shows the cheapest offer instead. Every offer is one tap away under Compare.