Senior Backend Engineer – Node.js / NestJS

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.