What you really keep per sale on Amazon, eBay, TikTok Shop and Shopify, in the US, UK, Germany, Spain and Japan. 5 languages (EN/DE/ES/PT/JA).

• Every fee line shows its rule and the marketplace’s own fee page with the date we read it (2026-10-22). The engine does whole-price vs “portion above” tiers, minimum fees, per-order fees, the eBay UK 0.35% regulatory fee, VAT and sales tax the way the marketplaces count them, and matches Amazon Japan’s own four worked examples exactly.
• Our own engine, not shared logins: it runs in your browser, nothing drops out, no waiting for other users, no device limit. Your costs never leave your device.
• Why monthly: fees keep changing — 4 marketplace rule changes already in 2026 and 2 more dated for December. We re-read the official fee pages every week. Save your products once; when a rule changes, every saved product is re-checked and shows its old → new margin.

Free: one marketplace at a time (fees, profit, margin, break-even price, price for your target margin, max ad spend) + the listing length checker.
Pro ($19.99/month or $149/year): compare all 4 marketplaces side by side · My products with fee-change re-check · bulk CSV for hundreds of SKUs · product check before you order stock · AI listing writer in 5 languages that keeps today’s limits (Amazon title 75 + Item Highlights 125, eBay 80, Shopify SEO 70/160), 300 listings a month.

A calculator, not tax advice. We sell the tool only: no promises about sales or income.