About SellerKitTools
What this site is
SellerKitTools is a free toolkit for people who sell on Etsy, Amazon, eBay, Shopify and other marketplaces. It started in 2026 with a simple observation: sellers spend too much time on repetitive math and image prep, and too much money on tools that charge a monthly fee for work a browser can do in seconds.
Every tool on this site is free to use with no signup and no account. Fee calculators show the real profit on a sale after marketplace fees. Image resizers prepare product photos to each platform's published size rules. Shipping calculators work out dimensional weight and box sizes. Listing tools check titles, generate tags and build SKUs.
How the tools work
Image tools run entirely in your browser using the Canvas API. Your product photos are never uploaded to a server, which matters for unreleased products and supplier images. Calculator inputs are never sent anywhere either. There is nothing to leak because nothing leaves your device.
Fee figures are estimates based on each marketplace's published fee schedule, for example Etsy's 6.5% transaction fee, Amazon's 15% referral fee on most categories, and eBay's 13.6% final value fee. Promotions, category exceptions and taxes can change real numbers, so always confirm current fees with the marketplace before finalizing prices.
Who runs the site
SellerKitTools is operated by WebInCave, a subscription web design agency for small businesses. The site is maintained alongside the guides on this blog, which cover the same seller workflows the tools are built for: pricing, product photos, shipping and listing SEO.
If a tool is wrong, a fee has changed, or a marketplace has a requirement we have missed, tell us through the contact page. Corrections are checked against the marketplace's own published rules before they go live.