Resellers cannot track true per item profit and inventory across many marketplaces without manual spreadsheets

Full time and side resellers move inventory across eBay, Poshmark, Mercari, Whatnot and Depop, each with its own fee structure (Whatnot 8 percent plus 2.9 percent plus 0.30 per transaction), payout schedule and report format. There is no clean per item cost basis, profit and tax view across all of them, so sellers maintain manual spreadsheets, paste in monthly CSV exports and still cannot answer what each item actually netted. Tracking works at five items a week and falls apart at fifty plus across shows and passive listings. The SellRaze listing and selling app has 33067 App Store ratings, showing the size of the active reseller base hitting this.