Stop Losing Money on Marketplace Fees — I Built Free Calculators for 10+ Platforms

If you sell on eBay, Etsy, Poshmark, or TikTok Shop, you already know the pain: every platform takes a cut, and the fee structures are deliberately confusing. Some charge listing fees, others take a percentage plus a flat rate, and a few even stack payment processing on top. I got frustrated trying to compare the real cost of selling the same item across different marketplaces. So I built a set of open-source fee calculators that break down exactly what each platform takes — no sign-ups, no ads, runs entirely in your browser. Why Marketplace Fees Are Harder Than They Look Take eBay: there's the final value fee (which varies by category), a per-order fee, promoted listing fees if you use ads, and PayPal/managed payments processing. Etsy layers transaction fees, payment processing fees, listing fees, and offsite ad fees. Poshmark uses a flat rate under $15 and a percentage above it. Comparing these side by side in a spreadsheet is doable but tedious. A dedicated calculator that knows the