Senior Full Stack Developer (Python + React)

Looking to build large-scale E-commerce solutions used by millions of customers? We are seeking a Senior Full Stack Developer with strong Python and React expertise to join a high-impact project for a leading pet products marketplace. This is a full-time remote opportunity based in Brazil. We at Sigma Software create innovative digital products that combine scalability, performance, and outstanding user experience. In this role, you will collaborate with experienced engineers and cross-functional teams to develop modern distributed systems and customer-focused web applications. Why join us? You will work with modern technologies, influence architectural decisions, and contribute directly to the growth of a large-scale E-commerce platform while enjoying flexible work conditions and professional development opportunities. CUSTOMER Our Customer is a leading marketplace specializing in pet products with a strong online presence and a large-scale digital commerce ecosystem. The company offers an extensive catalog of products for pet owners, including food, accessories, and healthcare solutions. Focused on customer satisfaction and innovation, the organization continues to expand its E-commerce capabilities to deliver seamless shopping experiences to millions of users. PROJECT The project focuses on developing a scalable and high-performance E-commerce platform for a major pet products marketplace. The solution is designed to support millions of customers while ensuring reliability, low latency, and fault tolerance across distributed systems. The team is building modern backend services, event-driven architectures, and responsive frontend applications to enhance customer experience and support business growth. Key Technologies: Python, React, REST APIs, GraphQL, AWS, Google Cloud, Azure, Linux, MongoDB, Cassandra, HBase, Redshift, Microservices Design, develop, and implement large-scale distributed systems capable of handling substantial data volumes Build scalable backend services and microservices using Python Develop and integrate REST and GraphQL APIs Create responsive frontend functionality using React Implement event-driven solutions to improve scalability and system performance Develop and execute unit, API, regression, and performance tests Optimize applications for scalability, reliability, and low latency Collaborate with cross-functional teams to troubleshoot and resolve production incidents Contribute to architecture discussions and technical decision-making processes 5+ years of software development experience with object-oriented programming languages, including Python Strong backend development experience with Python Experience building scalable distributed systems and microservices Practical experience with REST and GraphQL APIs Strong understanding of OOP principles, design patterns, algorithms, and data structures Commercial experience with React Hands-on experience working in Linux/Unix environments Experience with cloud platforms such as AWS, Google Cloud, or Azure Familiarity with relational and NoSQL databases including HBase, Cassandra, MongoDB, and Redshift Ability to work independently and collaboratively in distributed teams Upper-Intermediate English level or higher WILL BE A PLUS Experience with high-load E-commerce platforms Knowledge of event-driven architecture patterns Experience with performance optimization and observability tools Familiarity with CI/CD pipelines and DevOps practices Experience supporting production environments with high availability requirements PERSONAL PROFILE Strong problem-solving mindset Ownership and accountability Proactive communication skills Ability to work in fast-paced environments Team-oriented attitude with collaborative mindset