Ecom Calc Tools offers free online calculators for ecommerce sellers, marketers, and SaaS founders. It covers fees, profit margins, ROI, ROAS, CAC, CLV, churn, MRR, burn rate, taxes, and payment costs across Amazon, eBay, Etsy, Shopify, TikTok Shop, Stripe, and PayPal. Everything runs in the browser—no signup, no email wall, no data stored. Includes fee guides and comparison tools for better business decisions.