**Position Summary:** We are seeking a Senior Full Stack Developer with solid backend experience in Django and frontend experience in React. This person will play a strategic role in advanced technical support, investigating, resolving, and preventing issues. The primary focus will be incident investigation, bug fixing, optimizations, and supporting new features to assist the internal team, ensuring application stability and security. **Responsibilities:** **Backend (Django)** Analyze, debug, and fix issues in REST APIs and internal routines. Investigate data inconsistencies, bugs in new and existing workflows, webhooks, and other parts of the application that may require adjustments. Contribute to continuous improvement of architecture and development standards. **Frontend (React)** Fix bugs and unexpected behaviors in components, hooks, forms, and navigation flows. Investigate inconsistencies between frontend and backend, ensuring data synchronization. Improve user experience and maintain clean, scalable code. **Required Technical Skills:** Advanced experience with Django / Django REST Framework. Proficiency in React, Hooks, and State Management (Context, Redux optional). Webhooks and callback systems. Solid knowledge of PostgreSQL or equivalent relational databases. Knowledge of Docker. Familiarity with monitoring tools (DataDog, PostHog, etc.). **Preferred Qualifications:** Experience with queues and asynchronous tasks (Celery, Redis). Knowledge of automated testing (pytest, Jest, etc.). Experience with financial integrations (e.g., PicPay, Pagar.me, Mercado Pago). Experience in high-volume financial transaction environments. **Behavioral Profile:** Ability to operate under pressure during critical incidents. Clear communication with non-technical teams (support, customer service, operations). Proactivity in anticipating failures and proposing improvements. Organization and discipline in documenting processes and incidents. **Key Challenges of the Role:** Ensure stability and predictability of workflows. Address root causes of problems—not just superficial fixes. Maintain a healthy and reliable system, even during rapid expansion.