Marketplace Fee Calculator

WHAT IT DOES

Marketplace Fee Calculator scans product and listing pages across major e-commerce platforms, extracting selling price and shipping costs, then applies configurable marketplace fee structures to calculate net profit, profit margin, and break-even point. The tool supports percentage-based fees, fixed per-transaction fees, shipping fees, payment processing fees, and optional tax inclusion. It displays a detailed fee breakdown for each product and a summary of total revenue, total fees, total profit, and average margin across all products scanned. Marketplace presets are available for Amazon, eBay, Etsy, Shopify, BigCommerce, and Walmart.

WHERE IT RUNS

This userscript runs inside major e-commerce and marketplace platforms including Amazon, eBay, Etsy, Shopify, BigCommerce, and Walmart in your browser, powered by the free BotGentz extension. It operates entirely on the page you are viewing — it does not send your product data anywhere else. All data extraction and fee calculations happen locally in your browser. The script works on product listing pages, cart pages, and order summary pages.

HOW TO USE

Install the BotGentz extension, then install this userscript from the BotGentz catalogue. Navigate to a product listing page on any supported marketplace. Configure your settings — select your marketplace from the dropdown and click "Apply Marketplace Preset" to load default fee rates, or manually enter fee percentage, fixed fee, shipping fee rate, and payment processing fee. Set your currency symbol, toggle tax inclusion, and enter product cost manually. Click "Save Settings" to persist your configuration, then "Scan Page" to extract product data and calculate fees. The tool displays a detailed fee breakdown for each product and a summary of totals. Click "Copy Results" to export the full fee analysis to your clipboard.

HOW IT WORKS UNDER THE HOOD

The script uses a multi-strategy extraction approach to identify product price and shipping information across different marketplace platforms. It first attempts to locate product details using common price patterns and shipping fee patterns in the page text. It also looks for product titles using standard selectors like h1.product-title, .product-title, #productTitle, and .listing-title. For pages with multiple products, the script scans product tables using selectors like table.product-table, .listing-table, and .cart-table. The extracted data is then processed through the fee calculation engine, which applies the configured fee rates to calculate marketplace fees, shipping fees, payment processing fees, tax, net profit, profit margin, and break-even point. All calculations are performed locally and displayed in real time.

THE PANEL

The tool runs in the BotGentz panel, a draggable floating interface that stays on top of the page. You can drag the panel by its header, collapse it to a small bubble, and resize it. The panel remembers its position per site, so it stays where you left it when you return to your marketplace. Press Escape to close the panel when you are done. The panel includes settings for fee rates and marketplace selection, a results section showing the fee breakdown and profit summary, and action buttons for scanning, applying presets, and copying.

PLEASE NOTE

This tool requires the free BotGentz extension to run. Marketplace platforms frequently update their interfaces — if the tool stops working, check for an updated version or report the issue. All data stays in your browser and is never sent to any external server. The tool works only on the current page; to analyze products from multiple pages, scan each page individually. The tool extracts visible data only and cannot access data not loaded on the current page. Fee calculations are estimates based on configured rates and should be verified against your marketplace's official fee policies. The tool does not modify your product data — it only reads and displays information.