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Frequently asked questions
Only in your browser. Every item and calculation is stored locally via chrome.storage and is never uploaded.
No. Sellfin never touches your marketplace accounts and does no scraping — you type the numbers, it does the math.
Yes. Open Settings → Marketplaces & fees and edit any rate (percentage, per-order fee, payment processing, or the flat-fee rule). You can also add your own custom marketplace.
eBay, Etsy, Poshmark, Mercari and Depop are on by default; Amazon, Facebook Marketplace, Vinted, Grailed, StockX and Whatnot are included and can be switched on. Add more yourself any time.
Yes — all calculations run on-device. The only network call fetches display settings for the Support and Go-Pro links and sends no personal data.
Settings → Your data → Export backup (JSON) or Export items (CSV). Import the same files on another computer.