Senior Full-Stack Engineer: FastAPI / Next.js (Real-Time Collaboration)

Engagement: Full-time, hourly (~40 hrs/week) · Ongoing, feature-based scope Rate: $15/hour Timezone: Must overlap and stay reliably responsive during US Eastern (EST) business hours Location: Open globally: candidates based in China are not being considered for this role About the role: We build and maintain a suite of web applications, both internal tools and public-facing products for a US-based business in the resale / used-goods space. This is not greenfield work: you'll ship new features into existing, production codebases alongside a small, focused engineering team. Scope evolves feature by feature, so the skillset we need will shift over time. We need someone who ramps fast, contributes from day one, and adapts as priorities change. There's no fixed end date, the initial block of planned features runs a couple of weeks, with continued work as new features come up. What you'll do - Build new features across existing FastAPI (Python) backends and Next.js / React frontends - Design and implement real-time, multi-user collaboration features (live presence, concurrent editing, sync) using WebSockets / equivalent - Model and query data in PostgreSQL: schema design, performance, migrations - Integrate and tune search / caching layers (Meilisearch or equivalent) - Work directly with our technical manager, who runs a final technical interview before any offer Required - Strong, production-level Python + FastAPI (not tutorial-level) - Strong Next.js and React: frontend development is mandatory, not optional - Demonstrable real-time multi-collaboration app experience (WebSockets, presence, sync, conflict handling) Solid PostgreSQL (mandatory) - Hands-on experience with Meilisearch or another search / cache system How we work (please read before applying) These reflect issues we've hit before we screen hard for them: - Full-time focus. This is your primary engagement, not work squeezed in between other clients. Productivity that drops once you pick up side contracts won't work here. - You are the person who does the work. Whoever interviews is whoever joins no undisclosed substitutions, no swapping in someone else after the contract starts. - Reliable, proactive communication in clear written and spoken English is essential. You should be able to read a brief, ask sharp questions, and give updates without being chased. - Honor your committed availability and stay responsive during EST business hours. - We move quickly to end a contract if these expectations aren't met and we keep good people working as new features roll in. Engagement details - Hourly, full-time (~40 hrs/week), paid via Upwork - Initial scope ≈ 2 weeks of planned features; ongoing as new features come up (no fixed duration) - Skillset needs change between features - Day-one contribution expected To apply Send a short video note covering: - A real-time / multi-collaboration feature you personally built what the sync model was, how you handled concurrency or conflicts, and what broke during implementation. - Your FastAPI + Next.js production experience, with links to live work or repos if possible. - Confirmation of your full-time availability and EST overlap, plus your expected weekly hours. Vague or generic applications, or ones that can't speak to real-time work in detail, won't move forward.