Senior Full Stack Engineer (Mobile Frontend Oriented) (São Paulo)

About Us At Félix we are building the indispensable financial companion for Latinos in the US. We combine an AI-powered, conversational-first interface with real-time financial infrastructure to make cross-border money movement as easy as sending a text. Starting with fast, affordable remittances powered by AI and crypto rails, we are expanding into credit, savings, and wallet services to support the complete immigrant financial journey. Our ambition is to deliver a white-glove financial experience with the simplicity of a conversation to a community the traditional financial system has historically overlooked. We are a hyper-growth Series C company, backed by over $300 million in funding from top-tier global investors, including Andreessen Horowitz, QED, Castle Island, Switch Ventures, HTwenty, Monashees, General Catalyst Customer Value Fund. This isn't just about the numbers; it's a testament to the trust our investors have in our vision and our team. Additionally, Félix was selected as an “Endeavour Entrepreneur” and was a recipient of the CrossTech Fintech Startups Award. Joining Félix means you will be part of a team building a legacy, a company that will outlive us all. This is a rare opportunity to apply your skills to a deeply meaningful mission—serving a community that has been underserved for too long because we are obsessed with our customers. We get things done with urgency and focus, driven by extreme ownership over our impact. We collaborate without ego, fostering radical transparency and fierce loyalty so we can grow together. Because we aim for insanely great rather than just good enough, we stay insatiably curious—always experimenting, building the future today, and delivering a product that truly makes our users' lives better. About the Role As a key member of our engineering team, you will have a unique opportunity to shape the core technology behind our chat-driven platform. You will work on the Félix's Product Engineering team — a sophisticated system that not only processes high volumes of transactions but also delivers conversational experiences through integrated chatbots and natural language interfaces. Your role will be crucial in designing and enhancing interactive chat services and frontend (mobile and web) experiences that enable seamless, intuitive user interactions on platforms like WhatsApp, Web, and Mobile Application. We are looking for a Full Stack Engineer with deep expertise in mobile development (React Native, Flutter, or similar) and a solid understanding of backend logic and architecture. You will play a key role in building intuitive, high-quality mobile experiences while working across the stack to deliver seamless end-to-end solutions. Technology Stack We are technology agnostic and value candidates with diverse backgrounds. While familiarity with the following is helpful, your willingness to learn and adapt is paramount: Back-end: Python, Flask/FastAPI, REST APIs, Redis, SQL, gRPC Fronted: React, HTTP, HTML/DOM, JavaScript, CSS, AJAX Mobile: React Native (experience with Flutter or other mobile frameworks is equally valued) Cloud: Google Cloud services (Firestore, Cloud Storage, Pub/Sub, Google Artifact Registry, Cloud Run, BigQuery, Cloud Composer, etc.) Infrastructure: Kubernetes, Terraform, NewRelic, PagerDuty Responsibilities Mobile Experience: Design, develop, and iteration of our mobile application, building fast, reliable, and intuitive experiences with React Native or similar frameworks. Design & Architecture: Architect and implement high-performance, scalable backend microservices, including core components of our Chat Platform. End-to-End Ownership: Deliver features across the full stack, from the mobile UI to the backend services and APIs that support them, and contribute to backend logic. Collaboration & Mentorship: Foster the growth of junior developers through mentorship and best practice implementation, while collaborating closely with cross-functional teams including product, UX/UI, and business units. Continuous Improvement: Leverage customer feedback and analytics to iterate and improve our conversational experience, ensuring that our chatbots remain effective and user-friendly. Proficiency in English is required. Requirements These are the applicable requisites, although equivalent competencies in any of the above will also be considered: 5+ years of experience as a Software Engineer in a fast-paced environment. Strong mobile fundamentals: state management, navigation, performance profiling, offline and network handling, native integrations, and the app store release process. Solid understanding of backend logic and architecture: the ability to read, reason about, and contribute to backend services, design and consume REST/gRPC APIs, and work with databases and caching. Proven ability to build, ship, and iterate on software applications with an emphasis on real-world impact. Strong foundation in algorithms and data structures. Experience with web services, including SOAP and REST APIs. Familiarity with architectural patterns like Hexagonal Architecture, Event Driven Architecture, A/B Testing, Feature Flags, and Gradual Rollouts. Proven ability to leverage AI tools to enhance productivity and deliver high-quality work. Passion for building products that positively impact millions. Commitment to continuous learning and exploration of new technologies. Ability to thrive in a collaborative environment and contribute actively with innovative ideas. Excellent prioritization skills. Curiosity and/or experience in Fintech is an added advantage (though equivalent competencies will also be considered). Fluent or Advanced English. What We Offer Competitive salary Initial stock options grant Annual performance bonus Health, dental, and vision plans Work model: Currently fully remote, with a future transition to a hybrid setup. Continuous learning opportunities Unlimited PTO Paid parental leave Empowering opportunities for growth in a dynamic entrepreneurial environment Equal Opportunity Employer At Félix, we are committed to providing equal employment opportunities to all qualified employees and applicants without regard to race, religion, nationality, sex, sexual orientation, gender identity, age, or disability. This policy applies to all terms and conditions of employment, including recruitment, hiring, placement, promotion, training, compensation, benefits, and termination. Want to learn more about our privacy practices? Check out our Privacy Policy .