Full-Stack AI-Assisted Developer for Client Operating Systems

We build custom business operating systems that replace disconnected software, spreadsheets, and manual processes with applications designed around how a company actually works. We are hiring a full-stack developer to help us serve more clients without sacrificing speed or quality. You will improve existing production applications, turn approved PRDs into working software, resolve bugs, and create reusable technical foundations for future projects. Your first assignment: You will refactor an existing client application to improve its performance and load time. From there, you will work across new client builds, existing systems, and our internal development infrastructure. This is not a role for someone who only wants to complete isolated tickets. We need someone who can understand the intended outcome, make sound technical decisions, identify risks early, and take responsibility for getting the work into production. What you will do: - Refactor existing Next.js applications to improve performance, responsiveness, and maintainability. - Turn approved PRDs into tested, production-ready applications. - Build frontend features, backend functionality, and database architecture. - Design and maintain Supabase databases, authentication, storage, and application integrations. - Diagnose production bugs, resolve them quickly, and address their underlying causes. - Build integrations and automations between business systems. - Deploy and maintain applications after launch. - Create reusable components and processes that make future projects faster and more efficient. - Manage technical work across multiple client and internal projects. - Track your time accurately and communicate progress, blockers, and technical tradeoffs clearly. What you will own: You will have ownership over application architecture, database design, code structure, and implementation decisions. You will work directly with our CEO initially, with increasing collaboration with our COO. UI direction, product requirements, and final functionality will be reviewed and approved by the CEO. Required experience: - You have independently shipped production web applications. - You have strong working experience with Next.js. - You have built real applications with Supabase. - You understand relational database design and can explain the reasoning behind your architecture. - You have taken projects from requirements through implementation, deployment, and maintenance. - You know how to diagnose performance problems in existing applications. - You use AI-assisted development tools as part of your professional workflow. - You review, test, and correct AI-generated code instead of accepting it without validation. - You can explain technical decisions and surface risks before they become expensive problems. We care more about what you have shipped than your degree, title, or number of years in the industry. Helpful, but not required: - Experience with AWS. - Strong UI implementation skills. - Experience building internal business tools, operational dashboards, workflow software, or integrations. - Experience maintaining several active applications at the same time. What success looks like: During your first 30 days, you should be able to understand an existing client application, identify its primary performance constraints, and ship improvements that make it noticeably faster. Within approximately 60 days, you should begin turning what you learn into reusable standards, processes, or components that can support multiple client projects. By approximately 90 days, you should be able to manage work across multiple projects, execute approved requirements with limited supervision, and keep progress, quality, and technical risks visible. The specific projects will change as we take on new clients. The expectation will remain consistent: ship reliable software efficiently, resolve problems quickly, and leave each codebase easier to work with than you found it. Contract details: - Ongoing hourly contract. - Expected workload of 40 hours per week. - Rate of $25 USD per hour. - Remote, with a preference for developers based in Eastern Europe. - Meetings may be scheduled during U.S. Central business hours with 24 to 48 hours’ notice. - Hubstaff is used to allocate time across projects. - The contract and all payments will remain on Upwork. When client work is lighter, you will work on internal applications, reusable components, and improvements to our development process. How to apply: Begin your proposal by explaining why you think you'd be a good fit for this role. Then describe a measurable improvement you made to a production application. Then include: 1. Two or three relevant applications you helped ship. 2. A brief explanation of how you use AI-assisted development without compromising code quality. 3. UI screenshots if you have relevant interface work to show. A GitHub profile is not necessary. We are more interested in the production work you personally owned, the decisions you made, and the results.