Know your fees before you sell.

Most fee pages are written from the marketplace point of view, not the seller point of view. They tell you the official structure, but they do not always help you answer the practical question that matters before you list: after fees, shipping, and cost of goods, is this item still worth my time?

FlipCalc is built around that seller-side question. The calculator pages focus on the core fee math needed for pre-listing decisions, comparison pages show how the same item behaves on multiple marketplaces, and the guides explain the parts sellers usually misremember.

Fee assumptions are tracked in the local fee reference and mirrored into the platform configs used by the calculator engine. The intended workflow is straightforward: update the reference first, update the code second, update the public explanation copy third, and then rerun tests and a production build before publishing.

That process keeps the math, the written explanation, and the generated pages aligned. It does not pretend every edge case is already modeled. When a marketplace has optional ad programs, shipping discounts, or international variations, the site should say that explicitly instead of hiding the limitation.

FlipCalc is run by Maciej Dudziak through Maciej Dudziak IT Services. The business is based in Poland, and the site is maintained as a practical product for sellers who want clearer pre-listing fee decisions rather than generic content.

That means the trust layer should be explicit. The site should show who operates it, how the calculator is maintained, and where to find the company and contact details behind the product.

FlipCalc is strongest when you use it for core seller-fee planning. That includes the marketplace fee structure shown on the calculator page, shipping charged to the buyer, your actual shipping cost, item cost, and promotion cost when that input is supported.

Some marketplaces also have optional or situational costs that still need manual judgment. Examples include Etsy Offsite Ads, Poshmark shipping discounts, store-rate changes, taxes, refunds, or international variations.

FlipCalc now relies on a local SEO audit that checks the prerendered HTML output rather than only trusting the source files. That catches issues such as missing canonicals, malformed metadata, and shallow page depth before content changes are treated as done.

For fee changes, the intended order is still the same: verify the fee reference, update the calculator config, update the explanatory copy, run the build, and then audit the generated pages.

The best way to use FlipCalc is to treat it as a pre-listing decision tool. Run the likely sale price, test a slightly weaker outcome, and compare another marketplace if the margin is close.

If your sale involves unusual shipping choices, optional promotions, or marketplace edge cases outside the core model, use the calculator as the baseline and then make the final judgment with the platform guide in view.

That is also why the docs and remediation notes matter. The site is being built to make assumptions visible, improve coverage in passes, and leave a clear handoff for the next work session instead of hiding unfinished work behind vague claims of completeness.

The site is intentionally explicit about what is modeled and what is not. For a calculator in a money-sensitive workflow, honest boundaries are more useful than pretending every special case has already been solved.

That same principle shapes the UI now too. The site should feel trustworthy and deliberate, but still make the limits of the current fee model easy to understand before you lean on it for pricing decisions.