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Senior Backend Engineer – Node.js / NestJS

Celestial BI    Remote • Full-time

Senior Backend Engineer — Node.js / NestJS / AI

  • Company: Celestial BI
  • Employment Type: Full-Time
  • Experience: 3+ Years
  • Location: Sri Lanka / Remote
  • Seniority: Senior

About Celestial BI

Celestial BI is building modern software products that combine cloud technologies, data, automation, and Artificial Intelligence to solve real-world business problems.

We are looking for a Senior Backend Engineer with strong Node.js and NestJS experience who can take ownership of backend architecture, APIs, integrations, and AI-powered services.

What You'll Do

  • Design, develop, and maintain scalable backend applications using Node.js and NestJS.
  • Build robust REST APIs and backend services.
  • Design and implement database schemas and data access layers.
  • Integrate third-party APIs and external services.
  • Implement authentication, authorization, validation, and security.
  • Develop integrations with AI/LLM APIs and AI-powered services.
  • Build backend workflows supporting AI features and automation.
  • Debug and resolve production and performance issues.
  • Write clean, maintainable, scalable, and testable code.
  • Participate in architecture and technical decisions.
  • Conduct code reviews and maintain development standards.
  • Work closely with frontend engineers and project management.
  • Use AI development tools to improve development, debugging, testing, refactoring, and documentation.

Requirements

  • 3+ years of professional backend development experience.
  • Strong experience with Node.js.
  • Strong experience with NestJS.
  • Strong knowledge of JavaScript and/or TypeScript.
  • Strong experience building REST APIs.
  • Experience with relational databases such as PostgreSQL.
  • Understanding of authentication and authorization.
  • Strong understanding of asynchronous programming and backend architecture.
  • Experience with Git.
  • Strong debugging and problem-solving skills.
  • Experience using AI development tools such as Cursor, Claude, ChatGPT, GitHub Copilot, or similar tools.
  • Ability to independently design and implement backend solutions.

Nice to Have

  • Prisma / TypeORM.
  • Redis.
  • PostgreSQL optimization.
  • Docker.
  • CI/CD.
  • AWS / Azure.
  • Microservices.
  • Message queues / Kafka.
  • WebSockets.
  • OpenAI, Anthropic, Gemini, or other LLM APIs.
  • RAG systems.
  • Vector databases.
  • LangChain / LangGraph.
  • AI agents and automation.

What We're Looking For

We want an engineer who can own backend development and architecture.
You should be comfortable:

  • Making technical decisions independently.
  • Designing APIs and backend services.
  • Working with databases.
  • Investigating production issues.
  • Integrating new technologies and APIs.
  • Using AI tools effectively during software development.
  • Working closely with frontend engineers and product/project management.