Senior Full Stack Software Engineer (Python, React), Remote, Madrid/BarcelonaSe anima a todos los posibles solicitantes a que se desplacen y lean la descripción completa del puesto antes de presentar su candidatura.Help build high-performance web applications used by thousands of users.We're looking for a Senior Full Stack Software Engineer with a strong backend focus in Python and solid React experience to help design and scale modern web applications. This role is adecuado for someone who enjoys solving complex engineering challenges, making architectural decisions, and building systems designed for reliability and performance at scale.You'll work closely with engineers and stakeholders to deliver robust, user-friendly applications while contributing to both backend architecture and modern frontend improvements.About the RoleAs a Senior Full Stack Engineer, you will play a key role in shaping the technical direction of the platform. You'll lead backend architecture decisions, build scalable services, and help evolve the frontend experience using modern technologies.The platform supports thousands of concurrent users and high-frequency external integrations, so performance, stability, and scalability are critical.You'll also help drive engineering best practices, improve testing coverage, and contribute to continuous technical improvements across the stack.What You'll Be DoingLeading the design and development of backend services using PythonBuilding scalable APIs and services capable of supporting high traffic and concurrent usersContributing to modern frontend development using React and TypeScriptMaking key architectural and technical decisionsImproving system performance, reliability, and scalabilityWriting well-tested backend and frontend codeImplementing end-to-end and integration testing using PlaywrightCollaborating with engineers and stakeholders to deliver high-quality solutionsSupporting ongoing technology improvements and engineering best practicesWhat