SaaS Crosslisting Chrome Extension Development

Project Description I’m building a SaaS platform for online resellers that lets them create one master listing and publish it across multiple marketplaces from a single application. The core web app is already built on Lovable with Supabase. Now I need an experienced developer to build the Chrome extension and architect the backend integration that makes crosslisting work end-to-end. This is not a project to build the SaaS from scratch. The app already exists. Your role is to design and implement a production-ready Manifest V3 Chrome extension that connects the existing app to marketplaces like eBay, Poshmark, Mercari, and Depop. Product Vision The web app is the central source of truth. Instead of creating separate listings on every marketplace, users will: 1. Create a single listing in my app. 2. Upload photos, title, description, pricing, measurements, shipping details, etc. 3. Choose marketplaces (eBay, Poshmark, Mercari, Depop). 4. Publish from one place. The Chrome extension acts as the bridge between my app and each marketplace, using APIs where available and browser/DOM automation where public listing APIs do not exist. Target Marketplaces Initial focus: • eBay (public listing APIs available) • Poshmark (no public listing API, requires browser automation) • Mercari (browser automation) • Depop (browser automation) I am specifically looking for someone who has real experience building browser extensions that interact with websites, and who can recommend a robust long-term architecture for these marketplaces. Example Workflow • User creates a listing in my application. • Listing is stored in Supabase. • User selects marketplaces where they want to list. • Extension publishes the listing: • eBay via public API. • Poshmark / Mercari / Depop via browser automation and DOM interaction. • When an item sells, the system detects the sale and updates inventory / ends remaining listings to prevent overselling. This can start simple in the MVP but the architecture should be designed to support full synchronization over time. MVP Scope (This Project) For this phase, I need: • A Chrome extension built on Manifest V3. • Secure authentication between the extension and my Lovable/Supabase app. • Backend/API architecture to handle: • publish jobs created in the app and executed by the extension. • per-marketplace listing status tracking. • basic inventory sync and delisting foundations. • A working integration for at least one marketplace in production (eBay is the natural starting point; Poshmark is strategically important next). • Modular architecture so additional marketplaces can be added without rewriting the core system. Technical Stack • Lovable (existing React/Supabase app). • Supabase (auth, database, storage). • Chrome Extension (Manifest V3). • JavaScript / TypeScript. • React (preferred for extension UI/popup). What I’m Looking For I am not looking for a quick proof‑of‑concept extension. I need someone who can: • Help architect a scalable crosslisting platform. • Implement a solid MVP that can be extended reliably over time. Preferred experience: • Chrome extensions (Manifest V3, service workers, messaging, content scripts). • Marketplace integrations (eBay, Poshmark, Mercari, Depop or similar). • Browser automation and DOM manipulation. • API design and secure authentication flows. • Supabase or similar (Postgres + auth). • Familiarity with listing workflows for marketplaces or e‑commerce. Ownership All source code, intellectual property, and documentation produced under this project will belong to me upon completion. Work will live in my GitHub repository and be part of an ongoing product. Future Work This is intended to be a long‑term product, not a one‑off job. After the MVP, I plan to expand into: • Additional marketplaces. • Deeper inventory synchronization. • Automatic delisting when items sell. • AI‑assisted listing enhancements (titles, pricing, photo‑to‑price). • Analytics and reporting. I am interested in building a long‑term partnership with the right developer. When You Apply, Please Include: • Examples of Chrome extensions you have built (links or detailed descriptions). • Any marketplace automation or extension experience (eBay, Poshmark, Mercari, Depop, or similar). • A brief description of the architecture you would use for: • communication between the web app and the extension. • marketplace adapters (API vs DOM automation). • job/status tracking and inventory synchronization. • Your estimated timeline for an MVP that includes: • extension foundation. • one marketplace fully integrated. • auth and job/status plumbing.

Project ID: 40538882