How every number is verified

Each platform has a schedule file: the fee components, the exact sentences on the platform's page that state them, the page's URL, and the date the numbers were read. The calculator on the page computes from that file and nothing else.

The nightly check

Every night each platform's fee page is fetched and the exact sentences this site relies on — the ones quoted on each calculator page — are looked for in the page's text. If every sentence is still there, the page shows verified with the date the numbers were last reviewed and the date the page was last checked. If a sentence has disappeared or been reworded, the page shows under review until a person re-reads the schedule and updates the file — the calculator stays usable but is honest about its state. If the page could not be fetched, the page says so and keeps the last verified date. A fingerprint of all fee-bearing sentences is recorded as supporting evidence. Numbers are never changed by software.

Pinned to the platforms' own arithmetic

Where a platform publishes a worked example (eBay publishes two on its fees page), the calculator must reproduce it to the cent in an automated test, or the site does not build. Where a platform publishes only rates, the tests check derived arithmetic and say so on the page.

What is deliberately left out

Promotions, negotiated rates, store subscriptions unless stated, chargebacks and disputes, shipping label costs, and anything the platform has not published. Each page lists its exclusions.

How this site makes money

Some pages carry a sponsored link to the platform that page is about. If you sign up through one, this site receives a referral fee and you pay that platform's standard published price — there is no discount, and no better link. Three rules keep the money away from the numbers. A sponsored link never changes a computed fee. It appears only on that platform's own pages, never on a page comparing two platforms, so no comparison here has a paid side and an unpaid side. And no platform pays to be included, ranked, or described in any particular way; the platforms whose fees are calculated here do not pay for the calculators.

The code and the schedule files are public. Corrections that cite the platform's own page are applied.