Small tools that run on your own device
Your files are processed inside your browser. Nothing is uploaded, nothing is stored, and there is no sign-up or file limit.
Seller calculators (US)
Profit Margin CalculatorCalculate profit after marketplace, payment, shipping, and ad costs.Target Price CalculatorWork backward from your target margin to a minimum selling price.Break-even ROAS CalculatorFind the minimum ROAS and maximum ad cost per order.Etsy Fee CalculatorEstimate US Etsy listing, transaction, payment, and Offsite Ads fees.eBay Fee CalculatorEstimate US final value fees and profit for an eBay order.
Other languages
Why these tools work differently
Most online file tools upload your document to a server, process it there, and hand back a download link. That means your file leaves your machine, sits on someone else's disk, and you queue behind everyone else — which is also why those sites cap you at a few files unless you pay.
These tools use WebAssembly to do the same work inside your browser. Your file never travels, so there is no upload wait, no queue, no size cap, and nothing to delete afterwards. It also means these pages cost nothing to run, which is why there is no paywall.