Senior Full-Stack Team Needed to Extend Existing BilaGluten App with Multi-Merchant Marketplace

We are looking for an experienced full-stack development team to expand an existing production platform, BilaGluten, into a complete multi-vendor gluten-free marketplace ecosystem. This is NOT a new application built from scratch. The existing platform, UI, authentication, database, user accounts, safety-profile system, product/scanner ecosystem and other core functionality already exist. The selected team will work with the existing codebase and extend it. The engagement includes the complete marketplace scope, not a partial prototype: • Multi-vendor marketplace integrated into the existing BilaGluten platform • Partner/vendor onboarding and Partner Portal • Doctor/Professional Portal and appointment/request management • Customer marketplace experience integrated with existing accounts • Admin marketplace management and commission engine • Product/catalogue and order management • Payments and marketplace transaction flows • Partner types including transactional, discovery/listing and affiliate/referral partners • Mobile integration for iOS and Android using the existing application architecture • Notifications and relevant AI-assisted functionality • Arabic + English support, including proper RTL • Existing user and Safety Profile integration • Production deployment, QA and regression testing Current technology: Next.js, Firebase, Vercel, Shopify/commerce integrations and Capacitor for mobile. We want a team/company rather than a single temporary developer, because we are looking for reliable ongoing technical support and potentially a long-term relationship after this project. Project requirements Fixed-price engagement with milestone-based payments. Milestones will be agreed before development begins and paid after working deliverables are reviewed and accepted. Work must be done through our existing GitHub repository using PRs and proper version control. Existing functionality must not be broken while marketplace functionality is introduced. Strong QA and regression testing are required. Clean, scalable and production-ready implementation — not a temporary MVP that will need to be rebuilt later. Target completion: early October 2026. Budget: approximately $3,000 fixed price. Please apply only if you have reviewed the scope and believe your team can deliver within approximately this budget and timeline. In your proposal, please tell us: Whether you are an individual or a development company/team. Your proposed fixed price. Your realistic delivery date. Team members who would work on the project. Examples of marketplaces, multi-vendor platforms or similar systems you have built. Whether you provide post-launch support. Shortlisted candidates will receive the detailed functional specification before final milestone definition and contract award.