Fullstack Senior Developer

Here is a clear Upwork job description you can post: We are looking for a senior full-stack developer to help build and improve a web application using React, Python, and PostgreSQL. The ideal candidate should be strong in both frontend and backend development, able to understand business requirements, design clean technical solutions, and deliver production-quality code. You should be comfortable working independently, making technical decisions, and communicating clearly about progress, risks, and blockers. Key responsibilities: * Build responsive frontend features using React * Develop backend APIs and services using Python * Design and manage PostgreSQL database tables, queries, and integrations * Connect frontend and backend flows end-to-end * Write clean, maintainable, and well-structured code * Review existing code and suggest improvements * Debug issues across frontend, backend, and database layers * Work with AI coding tools, including Codex Agent, to speed up development while maintaining code quality * Help set up or improve development workflows, documentation, and deployment readiness Required skills: * Strong experience with React * Strong experience with Python backend development * Good experience with PostgreSQL * Experience building REST APIs or similar backend services * Ability to work independently as a senior developer * Good understanding of software architecture, code quality, and security basics * Comfortable using Codex Agent or similar AI coding assistants as part of the development workflow * Clear communication and ability to explain technical decisions in simple terms Nice to have: * Experience with FastAPI, Django, or Flask * Experience with authentication, role-based access, and user management * Experience with cloud deployment * Experience working on SaaS, AI, automation, or workflow-based applications When applying, please share: * Examples of React + Python projects you have built * Your PostgreSQL experience * Whether you have used Codex Agent or similar AI coding tools * Your availability and preferred working hours * A brief explanation of how you normally approach building a full-stack feature from requirement to delivery We are looking for someone reliable, practical, and senior enough to take ownership of the work with minimal supervision.