How EveryFee verifies its numbers

EveryFee exists because most marketplace fee calculators are wrong, stale, or hiding behind a sign-up wall. Our answer is a simple discipline: every rate on this site lives in exactly one data file per platform, and the calculator, rate tables, guides, and comparison tools all render from it. If a number is wrong, it's wrong in one place — and fixing it fixes everything.

Source and verification date on every rate

Each platform file carries the official fee page URLs it was taken from and the date it was last verified against them (currently 2026-10-14 across all platforms). Every calculator result shows that date with a direct link to the source, so you can check our arithmetic against the platform's own words before you trust it.

Weekly automated monitoring

A scheduled job fetches the official fee pages every week, normalizes the text, and diffs it against the previous snapshot. Any change opens an internal task that we verify by hand — only then does the rate file update, which redeploys the calculators, tables, FAQs, and changelog automatically. Where platforms hide rates behind seller logins (Amazon FBA fulfillment tiers are the known case), we say so and ask you for the number from your own Seller Central rather than hardcode values we can't re-verify.

What we don't do

• No accounts, no sign-up, no email gates — calculations run in your browser.
• No invented precision: if a rate can't be verified, the page tells you.
• No pay-to-rank: platform order in comparisons is computed, never sold.

Corrections

Fee pages change fast and we occasionally inherit their errors. If you spot a rate that doesn't match the official source, the fastest fix is an issue on our public repository — the changelog shows every correction we've ever made. Estimates on this site are exactly that: verify against official platform documentation before making pricing decisions.