Senior/Principal Full Stack Developer (Python + JavaScript/Typescript)

Design, develop, and maintain backend and frontend components for the revenue platform Build and optimize APIs, services, and integrations to ensure performance, scalability, and reliability Collaborate with cross-functional teams to define requirements, design solutions, and deliver features Contribute to backend development (Python) and frontend development (TypeScript/JavaScript) Participate in architectural planning and technical decision-making Ensure code quality through best practices, reviews, and testing Troubleshoot and resolve technical issues across the stack Mentor team members and share knowledge to enhance team capability 5+ years of professional software development experience, with a strong focus on Python Proficiency in JavaScript and TypeScript Hands-on experience with FastAPI and Temporal (or similar workflow orchestration tools) Solid understanding of backend architecture, API design, and microservices Experience integrating frontend and backend components in a full stack environment Strong problem-solving skills and ability to work independently on complex tasks Familiarity with cloud environments (AWS, GCP, or Azure) and CI/CD pipelines Excellent communication skills and ability to collaborate effectively in a distributed team Upper-Intermediate level of English Are you a seasoned developer ready to work on cutting-edge financial technology? We are looking for a Senior/Principal Full Stack Developer to join an ambitious global SaaS project in the finance domain. You will be part of a team building and optimizing mission-critical payment processing systems used by businesses worldwide. At Keystone AI , we value innovation, technical excellence, and collaboration. This role offers the opportunity to work with modern technologies across both backend and frontend, contributing to a platform that is reshaping revenue operations. Join us and enjoy working in an environment that supports professional growth, knowledge sharing, and impactful projects. CUSTOMER Our customer is a global SaaS company specializing in AI-native revenue platforms for modern finance and accounting teams. PROJECT Their solutions streamline subscription management, billing, and revenue operations for businesses of various sizes. The company is recognized for its innovation in automating complex financial workflows, integrating with leading payment gateways, and ensuring compliance with industry standards. Originally posted on Himalayas