SellSheet

SellSheet is a mobile + web app that helps secondhand sellers create one “master listing” and publish it across multiple marketplaces with consistent photos, sizing, condition notes, and shipping terms. It tracks where each item is posted, auto-updates price changes, and warns you when something sells so you can quickly delist elsewhere before you get double-sold. The app also generates platform-specific titles and descriptions (AI-assisted) and keeps a lightweight inventory ledger for COGS, fees, and profit per item. This is not a new marketplace—because competing with incumbents is a losing game. It’s an operations tool for people already selling on eBay, Poshmark, Depop, Facebook Marketplace, and others. Realistically, the hard part is marketplace integrations and policy compliance, so the MVP should start with a few platforms and semi-automations where APIs are limited.