Senior Software Engineer

Keystone AI is a leading advanced primary care provider, partnering with employer and union plan sponsors to improve health for millions of Americans. With nationwide onsite, nearsite, and network health centers, and virtual primary care, Marathon delivers a value-based model that enhances the healthcare experience for members and providers, while driving meaningful cost savings for plan sponsors. Marathon is proud to be certified as a Great Place to Work®, reflecting the company's commitment to building an inclusive, high-trust culture where all employees can thrive. Learn more at marathon.health ABOUT THE JOB As a Senior Software Engineer, you will play a critical role in driving the development of complex, multi-system features with a high degree of autonomy. You’ll independently own feature delivery from design through deployment, ensuring quality and scalability while mentoring junior engineers and fostering a culture of technical excellence. You’ll work closely with product and engineering teams to influence requirements during refinement and sprint planning, helping shape solutions that meet both business and technical goals. Your deep understanding of multiple frameworks and end-to-end workflows will enable you to apply advanced techniques to large-scale features and contribute meaningfully to system design and architecture. This role requires strong adherence to established development best practices, including code quality, testing, documentation, and CI/CD processes. Leading by example, you will be championing engineering standards and continuously improving how software is built and delivered. ESSENTIAL DUTIES & RESPONSIBILITIES End-to-End Feature Ownership: Independently design, develop, and deliver moderate to high complexity features across web and mobile platforms, ensuring quality, scalability, and alignment with business goals. Front-End Development: Build responsive and performant user interfaces using React and React Native, integrating seamlessly with backend services and ensuring consistent user experience across platforms. Backend Engineering: Implement robust backend systems using C#, TypeScript, Ruby on Rails, and RESTful APIs. Develop and maintain microservices that support distributed, scalable applications. Cloud & Infrastructure: Leverage AWS services including ECS, EKS, Lambda, API Gateway, S3, and CloudWatch to deploy and monitor applications. Use Terraform for infrastructure-as-code and manage event-driven architectures with Debezium, Kafka, and SNS/NServiceBus. Database Development: Design, query, and optimize relational databases using SQL and PostgreSQL, ensuring data integrity and performance across services. System Design & Architecture: Contribute to system-level design decisions, applying advanced engineering techniques and understanding of end-to-end workflows to build scalable, maintainable solutions. Mentorship & Collaboration: Mentor junior engineers, conduct code reviews, and foster a culture of continuous learning and technical excellence. Collaborate cross-functionally with product managers, designers, and other engineering teams to refine requirements and plan sprints. Process Leadership: Champion and adhere to established development best practices, including CI/CD, automated testing, version control, and documentation standards. Drive improvements in team processes and engineering efficiency. Technical Strategy: Influence technical direction by evaluating new frameworks, tools, and patterns. Ensure alignment with organizational standards and long-term scalability. QUALIFICATIONS BS or MS in computer science or related field and 5+ years of software development experience including 3+ years in a technical leadership role or equivalent combination of education and experience. Advance expertise of working on development teams in an Agile Scrum environment in the following technologies: React, React Native, C#, Typescript, RESTful API’s, and microservices. DESIRED ATTRIBUTES Strong understanding of end-to-end workflows, system design, and architectural patterns. Proven ability to apply advanced engineering techniques to large-scale features and systems. Demonstrated adherence to development best practices, including CI/CD, automated testing, code reviews, and documentation. Familiarity with project management, software development, and ticketing tools (Azure DevOps, Freshworks) AWS Certified Developer certification or equivalent Ability to influence product requirements and contribute meaningfully during refinement and sprint planning. Excellent communication and collaboration skills across cross-functional teams. Operates with a high degree of autonomy and accountability. Proactive in identifying technical risks, proposing solutions, and driving continuous improvement. Pay Range: $110,000 - $145,000/yr The actual offer may vary dependent upon geographic location and the candidate’s years of experience and/or skill level. We are accepting applications for thi