Back End Developer

# Job Description: Senior Backend Engineer — Node.js & PostgreSQL

**Experience:** 4+ Years

**Employment Type:** Full-Time

**Location:** India Remote

## About the Role

We are looking for a highly skilled and experienced Backend Engineer with strong expertise in Node.js, Express.js, PostgreSQL, and real-time system integrations. The ideal candidate must have hands-on experience building scalable, secure, high-performance backend systems, integrating third-party services, optimizing complex database queries, and managing real-time communication infrastructure.

The candidate should be capable of independently handling backend architecture, database design, performance optimization, production debugging, and system reliability.

## Key Responsibilities

### 1. Backend Development

• Design, develop, and maintain scalable RESTful APIs using Node.js and Express.js.

• Build modular, maintainable, and production-ready backend services.

• Implement authentication, authorization, role-based access control, validation, and API security.

• Develop efficient business logic and reliable transaction-processing workflows.

• Write clean, reusable, testable code following industry best practices.

### 2. PostgreSQL & Database Optimization

• Design and maintain complex relational database schemas, relationships, constraints, and indexes.

• Write advanced SQL queries involving joins, subqueries, CTEs, aggregations, window functions, and transactions.

• Optimize slow queries using `EXPLAIN ANALYZE`, indexing strategies, and query-plan analysis.

• Handle database concurrency, locking, deadlocks, isolation levels, and transaction consistency.

• Optimize database performance for high-volume read/write operations.

• Manage connection pooling, pagination, data integrity, and database migrations.

• Work with PostgreSQL using an ORM such as Prisma or Sequelize while retaining strong raw SQL skills.

• Diagnose production database bottlenecks and implement long-term performance improvements.

### 3. Redis & Caching

• Implement Redis caching strategies to reduce database load and improve API response times.

• Work with Redis data structures, TTLs, cache invalidation, and cache consistency.

• Use Redis for distributed locking, rate limiting, session management, and pub/sub where appropriate.

• Troubleshoot Redis performance and connection issues in production.

### 4. Real-Time Communication — Socket.IO & MQTT

• Develop real-time features using Socket.IO and WebSockets.

• Implement event-driven communication, rooms, namespaces, and efficient event broadcasting.

• Integrate MQTT brokers for message publishing, subscriptions, and device/service communication.

• Handle reconnection, message delivery, duplicate events, QoS, and failure recovery.

• Design scalable real-time systems with appropriate Redis adapters, message brokers, and horizontal scaling strategies.

• Optimize event processing and broadcasting under high concurrency.

### 5. Third-Party API Integrations

• Integrate external REST APIs and WebSocket-based services.

• Implement API authentication, request signing, retries, timeouts, and rate-limit handling.

• Build resilient integrations with circuit breakers, backoff strategies, and graceful failure handling.

• Normalize third-party data and handle inconsistent payloads and provider outages.

• Monitor integration health, latency, failures, and API usage.

• Troubleshoot complex integration issues across multiple services.

### 6. Performance, Reliability & Production Support

• Identify and resolve memory leaks, CPU bottlenecks, slow APIs, and high-latency operations.

• Optimize asynchronous processing and Node.js event-loop performance.

• Implement structured logging, monitoring, health checks, and error tracking.

• Use queues and background workers such as BullMQ when asynchronous processing is required.

• Diagnose production issues and deliver reliable, scalable solutions.

• Write unit and integration tests and participate in code reviews.

### 7. Deployment & Infrastructure

• Work with Linux-based production environments and process managers such as PM2.

• Understand Docker, CI/CD pipelines, environment configuration, and deployment workflows.

• Collaborate with DevOps engineers on production deployments, monitoring, and scaling.

• Understand load balancing, horizontal scaling, and distributed-system fundamentals.

## Required Technical Skills

• **Backend:** Node.js, Express.js, JavaScript, TypeScript

• **Database:** PostgreSQL, advanced SQL, query optimization, indexing, transactions

• **ORM:** Prisma, Sequelize, or equivalent

• **Caching:** Redis

• **Real-Time:** Socket.IO, WebSockets, MQTT

• **Integrations:** REST APIs, WebSockets, third-party service integrations

• **Background Processing:** BullMQ, Redis queues, or equivalent

• **Tools:** Git, Postman, Linux, Docker, PM2

• **Architecture:** REST API design, event-driven architecture, concurrency, distributed systems

• **Quality:** Unit testing, integration testing, debugging, logging, and monitoring

## Must-Have Experience

• At least 4 years of professional backend development experience.

• Strong practical knowledge of Node.js and Express.js in production environments.

• Proven ability to write and optimize complex PostgreSQL queries.

• Hands-on experience with Redis, Socket.IO, and MQTT integrations.

• Experience troubleshooting production issues involving databases, third-party APIs, and real-time systems.

• Strong understanding of transactions, concurrency, race conditions, and data consistency.

• Ability to independently analyze problems and deliver production-ready solutions.

## Preferred Qualifications

• Experience building high-traffic applications or real-time transactional platforms.

• Experience in sports, gaming, fintech, trading, or other latency-sensitive systems.

• Familiarity with AWS, cloud infrastructure, message brokers, and distributed caching.

• Experience with PostgreSQL performance tuning and database observability.

• Experience with event-driven microservices and background job processing.

## What We Expect From the Candidate

We are looking for an engineer who can do more than develop API endpoints. The candidate must understand how the entire backend works, from incoming requests and third-party integrations to database queries, real-time events, caching, and production deployment.

They should be able to investigate complex issues independently, identify root causes, improve performance, and build reliable backend services that can scale with business growth.

## Application Requirements

Candidates should share their updated CV along with details of their experience in Node.js, Express.js, PostgreSQL query optimization, Redis, MQTT, Socket.IO, and third-party API integrations. Applicants should also mention relevant production systems they have developed and performance or reliability challenges they have resolved.