Credits and licences
Last updated 2026-10-28
Our own code
The rules engine (fees, profit, reporting thresholds), the calculators and the page layouts are written for this site. Apart from the visit counting described in the Privacy Policy, the pages load only files from this site.
Third-party material
| Name | Used for | Licence |
|---|---|---|
| fflate 0.8.3 | Zips the parts of the Excel (.xlsx) files you download | MIT |
| Marketplace fee pages, tax authority pages and laws | Every rate, threshold and rule is read from the official page listed on the Sources page and on each calculator; no text or table is copied from them | Facts, no licence needed; the marketplaces and authorities are not affiliated with ResalePocket |
Open source we checked and did not use
The rules engine has no open-source equivalent: the fee rules are data from each marketplace’s own pages, maintained with dated sources and tests. For money arithmetic we use exact integer cents and basis points instead of a decimal library (big.js, decimal.js and dinero.js were compared; none was needed for percentages of cent amounts). For the browser ledger we use IndexedDB directly because the ledger needs only add, list and delete (Dexie.js was compared). For CSV we use a small parser of our own that handles quoted fields. The full comparison is in the site’s open-source notes.