Remote (Brazil, Argentina) - Experienced Full-stack (React & Python) Contractor

At Stack Builders we partner with clients to build high-quality, production-ready software with clear goals, strong engineering practices, and minimal waste. For this engagement, we are supporting a client building AI-enabled automated cybersecurity and insurance platforms. The work focuses on turning well-defined requirements and validated prototypes into reliable, scalable SaaS systems, while shaping the next generation of automated risk analysis tools. We are looking for a senior full-stack engineer who can take ownership of features end-to-end and work effectively in an AI-assisted development environment. What You’ll Work On Build a production system based on an existing React prototype Implement: Interactive data visualizations Risk scoring and analysis logic Backend integrations and supporting pipelines Collaborate on evolving data models as the product matures Build frontend interfaces for an automated Security Operations (SOC) platform Integrate with backend services handling telemetry, analytics, and automated workflows Support systems designed for heavy background data processing in a B2B context Early-stage implementation based on defined product direction Frontend-heavy work (UI, UX, interactions) and backend-focused work (APIs, data handling, business logic) You will spend more time directing, reviewing, and refining than typing every line yourself You are expected to use AI to generate initial implementations and provide the AI with codebase context (existing patterns, schemas, conventions) Critically evaluate AI output for correctness, edge cases, and maintainability Required Experience Senior-level experience building SaaS applications end-to-end Strong proficiency in React and Python Experience with API design and integration, databases, and data pipelines Ability to work from: Clear PRDs Prototypes Defined data models AI-First Mindset You are comfortable using AI coding tools (Claude Code, Copilot, Cursor, ChatGPT) as part of your daily workflow. You can direct AI with clear prompting, refine its output, and detect subtle correctness or security issues. You value AI as a productivity multiplier—not a crutch—and you never copy AI output blindly. Ways of Working You speak English fluently or at a professional level. Your communication is clear, organized, and assertive. You can work a minimum of 4 hours overlapping with the US Eastern timezone for real-time collaboration with the client. You enjoy working in a small, senior, high-ownership team. You are eager to learn, grow, and have fun while addressing meaningful challenges. Benefits 100% remote and flexible modality. A human-centered experience in a people-first company. Challenging, full-time, and long-term projects with globally admired companies. A strong learning culture and regular pairing sessions to build high-quality code while sharing knowledge. Opportunities for conference participation, OSS contributions, tutorials, blog posts, and technical talks. Exceptionally talented and passionate coworkers. Timely payments, with the flexibility to choose the payment date modality that best suits your needs. A Stack Builders community to support you and grow with you Ready to become our next builder? We hope you’ll join us More than our EEO statement , this is what makes us a Great Place to Work : Stack Builders is proud to be an equal-opportunity employer. We are committed to creating a safe and inclusive work environment and don’t tolerate discrimination or harassment during the hiring process or time of employment. All team members and candidates are assessed and appreciated for their attitude, qualifications, and potential - regardless of race, religion, color, nationality, sexual orientation, gender expression or identity, age, disability, marital status, pregnancy, and other characteristics protected by law. Learn more about us by visiting our website, where you can find blog posts, tutorials, and testimonials from our team and clients. #J-18808-Ljbffr