Full-Stack developer (Next.js/Stripe/Railway) to take over & complete marketplace web app

We are building a two-sided marketplace web app for the German market (B2C/B2B service booking with chat, offers, and order workflow). The good news: the app is already fully worked out with Claude – concept, screens, data model, workflows, state machine, and large parts of the code are ready. You will not start from a blank page and you will not have to guess what we want. What we need is an experienced developer who takes this complete blueprint and turns it into a production-ready web app, deployed on Railway – and who then stays on board. This is planned as a long-term engagement: after launch, you will continue to maintain the app and develop new features with us on an ongoing basis. WHAT YOU'LL BE WORKING ON (high level): - Developing the full web app based on the existing specification and code (Next.js / TypeScript / PostgreSQL) - User accounts and roles, job postings, offers, real-time chat - Order workflow with state machine (draft → published → awarded → completed) - Admin area, GDPR-compliant setup (EU hosting) - Connecting to our existing billing system via API (billing and invoicing are handled on our side, the API is provided by us) - Testing, production deployment on Railway, CI/CD, monitoring, backups - After launch: ongoing maintenance, support, and development of new features - Full details, specification, and existing code will be shared with shortlisted candidates WHAT WE NEED FROM YOU: - Proven track record: you have built and shipped several complete web apps yourself (not just components or landing pages) - Strong in Next.js / React, TypeScript, PostgreSQL - Hands-on experience deploying and running apps on Railway - You use Claude Code in your daily workflow and know how to work efficiently with an AI-generated specification and codebase - Experience integrating third-party REST APIs - Clean, documented code – the source code belongs to the client - Reliable, available long-term, and good at communicating - Good English; German is a plus HOW TO APPLY – PLEASE READ CAREFULLY: We get a lot of generic proposals, so to show you have actually read this, start your proposal with the word KORMORAN. Proposals without it will not be considered. Then include: 1. Links to 2–3 web apps you built yourself (live URL and/or repo), with a short note on your role 2. At least 2 references (previous clients we can contact, or Upwork reviews for comparable projects) 3. A short description of how you use Railway and Claude Code in your workflow 4. Your availability over the next 3–4 months and beyond, plus a rough fixed-price estimate for the build and your hourly or monthly rate for ongoing work Shortlisted candidates will receive the full specification and existing code under NDA and will be asked for a detailed offer based on it. Build phase as milestone-based fixed price, ongoing work hourly or on a monthly retainer. Start: as soon as possible.