Backend Development Build large-scale web applications and services Design and develop REST APIs and possibly GraphQL APIs Create scalable server architectures Optimize application performance and reliability Handle authentication, authorization, and security Build microservices and distributed systems Programming Languages Node.js + TypeScript (expert) Express, NestJS, Fastify, etc. Golang High-performance backend services Concurrent systems using goroutines PHP Maintain or modernize legacy systems Databases Design MongoDB databases Create efficient schemas and indexes Optimize queries and performance Handle data migration and scaling Frontend Integration Connect backend APIs to React applications Work with React developers or build React interfaces themselves Implement authentication, state management, and data fetching DevOps / Infrastructure (likely) With 8 years building scalable systems, they probably also have experience with: Linux servers Docker Cloud platforms (AWS, Google Cloud, Azure, etc.) CI/CD pipelines Monitoring and logging Roles They Could Fill Senior Backend Developer Full-Stack Developer Software Engineer API Engineer Technical Lead Startup CTO (especially for early-stage startups)