Opening
When I launched ScoreMyASIN in early March, I knew there was a problem I couldn't solve yet. The fees were estimates. ScoreMyASIN scores Amazon products for FBA sellers — you paste in an ASIN, it pulls Keepa data, runs it through a scoring algorithm built on 7 years of wholesale experience, and gives you a BUY, WATCH, or AVOID verdict with full economics. Profit per unit, ROI, monthly profit estimate, risk flags, sales estimate. But the Amazon fees — the referral fee, the FBA fulfillment fee — were calculated using category-based estimates. Not real numbers. And if your fees are slightly off, everything downstream is slightly off. Your profit. Your ROI. Your score.
What the SP-API actually is
Amazon's Selling Partners API is the official programmatic gateway to Amazon's marketplace data. It's what serious seller tools use to pull real fee estimates, check gating status, verify hazmat classification, and more. You don't just sign up — Amazon reviews your application and approves or rejects it based on how you intend to use the data. I submitted my first application in late February. Rejected within days. The reason: I'd mentioned a third-party data provider in the application description, and Amazon doesn't allow references to external data providers in SP-API applications. Fair enough — I rewrote it and resubmitted on February 25th. Then I waited. Weeks went by. I chased it. Then on March 25th, the email landed: approved. I shipped it to production three days later.
What's live now
Three things changed the moment I connected it: Real fees. Every score now uses actual Amazon fee calculations — referral fee, FBA fulfillment fee, closing fee — calculated by Amazon's own API at the exact sell price. Not estimates. The fee source is logged as 'sp-api' in every result so you can see it's real data. Real gating. ScoreMyASIN now checks whether you're actually approved to sell a product before scoring it. If you're blocked, it tells you. If you need approval, it tells you. If you're open to sell, it tells you. This was previously a gap — now it's live. Real hazmat detection. Dangerous goods are now automatically identified and penalised in the scoring algorithm. Previously a null — now a live flag.
What this means in practice
I tested it today on a live ASIN — B005BV0KI0, a veterinary product on Amazon UK, selling at £15.45. The SP-API returned a referral fee of £2.46 and an FBA fee of £2.94. I cross-checked it against Amazon's own revenue calculator. Almost exactly the same. That's the difference between a tool that estimates and a tool that knows.
What's next
SP-API also unlocks better variation-level data as the integration matures, and will support EU marketplace fee calculations as I expand ScoreMyASIN across Amazon.de, Amazon.fr, and the rest of the European markets. If you want to try it, the free plan gives you 5 scores a day — no card required. scoremyasin.com Full changelog at scoremyasin.com/changelog — updated every week. — Chris
