How it works
- 1
Search
Enter a supplement name, brand, or category — for example "magnesium", "omega 3", or "Solgar". Certwell searches across product names, brands, and categories.
- 2
See certified products
Results show certification badges from NSF, USP, Informed Sport, IFOS, and IGEN. Certified products are surfaced clearly so you can tell at a glance which options have been independently verified.
- 3
Filter by certification
Use the certification filters to narrow results to a specific body — for example, IFOS for fish oil or NSF for sports supplements.
- 4
Buy from a UK retailer
Each product page lists UK retailers where you can buy it. Click through to check availability and price.
No certified match found?
If a product you search for has no supported certification, Certwell shows certified alternatives in the same category so you can find a higher-trust option.
Where the data comes from
The catalog is built from a small set of curated source files rather than scraped from retailer pages on demand. There are four:
- Products. Canonical product records — name, brand, category, and a short description.
- Certifications. The five supported schemes — NSF Certified for Sport, USP Verified, Informed Sport, IFOS, and IGEN — with links to each programme.
- Product–certification links. Each link records the certifying body, the source URL on the body's public database, and the date the listing was last verified.
- Retailer listings. UK retailer URLs for each product, with prices and review counts where available.
How certifications are verified
Each certification link points back to the certifying body's own public database — for example, NSF's sport listing pages, Informed Sport's lot-by-lot search, or Nutrasource's certifications portal for IFOS and IGEN. Certwell does not self-certify, accept payment for certification status, or interpret what a certification means beyond what the issuing body publishes.
When you click a certification badge on a product page, you can follow it to the source listing and confirm the status yourself. This is the same standard recommended in the certification reference pages: the badge on a brand site is not a substitute for checking the batch or product against the body's own database.
What “active retailer” means
A retailer listing is marked active when the destination URL still resolves to the product on the retailer's site at the time of the most recent review. Listings are marked inactive when the product has been delisted, the URL redirects elsewhere, or the retailer has changed the URL structure.
Inactive listings are not deleted — they remain in the source data so that historical context is preserved — but they are hidden from product pages until a fresh URL is found. The result is that some products show fewer retailers than they did previously; that is intentional.
How retailer ranking works
Retailer listings on a product page are ordered by popularity signals collected from the retailers themselves — primarily the number of customer reviews recorded against the listing — not by commission rate. Some links are affiliate links; others are plain links to retailers Certwell has no commercial relationship with. Both types are surfaced on equal footing.
A retailer never pays to be listed, never pays to outrank another retailer, and the affiliate disclosure in the site footer applies to every page that contains a retailer link.
Refresh cycle
The certifying bodies update their own databases on their own schedules — some weekly, some monthly, some on a rolling per-batch basis. Certwell refreshes its certification links periodically and rebuilds the catalog from source. Because builds are reproducible, stale entries can be re-validated and replaced cleanly without editing the production database.
For high-stakes use — an athlete subject to drug testing, for example — always verify the specific batch on the certifying body's site before relying on it.
What Certwell does not do
- Sell supplements. Certwell links to UK retailers; it does not fulfil orders, hold stock, or collect payment.
- Issue certifications. The site surfaces existing certifications from independent bodies. It does not test products or award marks of its own.
- Rank brands by quality beyond certification status. A brand with one certified product appears alongside a brand with twenty. The catalog reflects what is independently verified, not who has paid for placement.
- Cover every supplement on sale. Coverage is broadest for sports supplements, fish oil, and common vitamins, where certification programmes have the most participation. Niche or non-certified categories are intentionally narrower in scope.
Absence of certification does not mean a product is unsafe — it means it has not been independently verified by one of the supported bodies. See what each certification covers or get in touch with corrections or coverage requests.