Backend Developer Node.js - Distributed Systems

Recex Pvt Ltd.; Kolkata District; Presencial; INR 1.200.000 - 2.400.000; Jornada completa

Descripción de la vacante

Recex Pvt Ltd. is seeking a Senior Backend Developer to own client engagements end-to-end, from discovery and architecture through build and operation. You will shape backend direction on multiple SaaS projects for diverse markets, focusing on distributed systems, real-time patterns, and observability.

The role emphasizes design of APIs, async pipelines, caching, and leadership of a small team, with direct client interaction and milestone planning in a fast-paced environment.

Formación

• 5–9 years of backend development experience in a senior or lead role.
• Strong Node.js/TypeScript with API design and cloud-scale SaaS exposure.
• Experience with distributed systems, async patterns, and real-time patterns.

Responsabilidades

• Own client engagements end-to-end from discovery to operation.
• Design async architectures, caching, and real-time data flows.
• Mentor junior developers and participate in hiring and process improvements.
• Lead client communications and present technical approaches to stakeholders.

Conocimientos

Node.js

TypeScript

Express.js

Redis

MongoDB

PostgreSQL

REST

GraphQL

gRPC

Kafka

WebSockets

Observability

AWS

Kubernetes

SaaS

Leadership

Herramientas

Docker

RabbitMQ

BullMQ

AWS SQS

Terraform

Pulumi

Descripción del empleo

Senior Backend Developer INSIGHTSTAP / SDTC DIGITAL Hiring Details

Senior Backend Developer Node.js - Distributed Systems - Client Services - 5 to 9 years Internal Document -

Senior Backend Developer Department Technology / Development Reports To Founder / CTO Employment T

ype Full-time, Contract-to-Hire (C2H) Location Kolkata (Work From Office)

Working Days Monday to Friday (Saturday & Sunday off) Experience 5 - 9 years Notice Period Preferred Immediate to 45 days

About the Role We are hiring a senior backend engineer to own client engagements end-to-end - from discovery and architecture through build, deploy, and operate. You will lead the backend technical direction on multiple SaaS projects for clients across the US, UK, Singapore and other markets, and will be a multiplier for the rest of the team. This is a high-ownership backend role with a strong distributed-systems flavour. Expect to design APIs, async pipelines, caching layers, real-time fan-out, and observability in production - not just write feature code. You will also lead client conversations and shape the engineering standards as we scale the team.

Key Responsibilities

Project Ownership (60%)

• Own client engagements end-to-end: discovery, scoping, technical design, build, deploy, and operate.
• Design async architectures: queues, workers, retries, dead-letter queues, idempotency, and back-pressure for long-running workloads.
• Design caching strategies with Redis (cache-aside, write-through, distributed locks, rate limiting) and own cache-invalidation correctness.
• Implement real-time and Pub/Sub patterns - WebSockets, Server-Sent Events, Redis Pub/Sub, Redis Streams - for streaming output and job-progress fan-out.
• Lead complex integrations (voice AI platforms, CRM and ERP APIs, payment systems, OAuth multi-account flows).
• Own production reliability, observability (logs, metrics, traces), and performance for delivered systems.
• Drive code-quality standards, and repo hygiene across the team.

Client Leadership (25%)

• Lead client requirement-gathering and scoping calls.
• Propose technical approaches - including async, caching, and tenancy decisions - and present them to non-technical stakeholders.
• Provide honest effort estimates and milestone breakdowns.
• Manage day-to-day client communication on owned engagements.

Team Leadership (15%)

• Mentor 2 to 3 junior developers; conduct code reviews and technical 1:1s.
• Drive internal initiatives and tooling improvements.
• Participate in interviewing and hiring for the engineering team.
• Run postmortems and feed learnings back into process and standards.

Required Qualifications

Technical Skills (Must Have)

• Backend: Strong Node.js, TypeScript, and Express.js; FastAPI experience a plus; clean API design and versioning; comfort with REST and at least one of GraphQL or gRPC.
• Databases: Production experience with both MongoDB and PostgreSQL; schema design, indexing, query optimisation, transactions.
• Caching with Redis: Production use of Redis for caching, sessions, rate limiting, and distributed locks; understanding of cache-aside vs write-through, TTL strategies, and invalidation correctness.
• Async & Messaging: Production experience with at least one of RabbitMQ, BullMQ, Kafka, or AWS SQS for background jobs, fan-out, and long-running workloads; comfort with retry, exponential backoff, idempotency, and dead-letter queues.
• Real-time & Pub/Sub: Implemented Pub/Sub patterns (Redis Pub/Sub, Redis Streams, Kafka topics, or equivalent) and WebSocket / Server-Sent Events for client streaming and job-progress fan-out.
• Observability: Structured logging, metrics, and distributed tracing in production.
• Cloud & Containers: AWS or GCP at production scale; Docker; Cloudflare R2 / Workers experience welcome; basic Kubernetes a plus.
• SaaS Architecture: Multi-tenancy patterns, payment / subscription flows, SSO / OAuth multi-account, alerting and on-call basics.
• Leadership: Demonstrable experience mentoring engineers or leading a small team or workstream.

Experience Requirements

• 5 to 9 years of full-stack web development experience, with the most recent role at a senior or lead level.
• Owned at least 2 production systems end-to-end through architecture, build, deploy, and operate.
• Designed and operated at least one production async / queue-based pipeline (background jobs, ingestion, batch processing, or similar).
• Track record of working directly with clients or external stakeholders on technical scoping.

Soft Skills

• Excellent problem-solving and analytical thinking.
• Strong communication skills in English.
• Ability to manage multiple workstreams and shifting priorities.
• Client service mindset with attention to detail.
• Adaptability and a startup mentality.

Preferred Qualifications

• Production experience with LangChain or LangGraph; RAG pipelines; vector DB selection (pgvector or another vector DB); LLM cost / latency tradeoffs; prompt engineering and basic evals.
• Building and operating RAG, agentic, and AI orchestration pipelines using LangChain, LangGraph, or equivalents.
• Internal AI-tooling initiatives such as MCP server rollout, custom slash commands, and CLAUDE.md discipline.
• LLM-specific observability with LangSmith, Langfuse, Helicone, or equivalent.
• At least 1 production AI feature shipped in the last 12 to 18 months.
• Comfortable with frontend (React.js, Next.js) for occasional cross-stack work - a plus, not required.
• Experience with voice AI platforms (Retell AI, Vapi, ElevenLabs).
• Production agentic AI orchestration (not just demos).
• Multi-tenant B2B SaaS design or operations.
• Comfort with Claude Code workflows, MCP servers, and modern AI-assisted engineering practices.
• Kafka or NATS at production scale; Elasticsearch or OpenSearch for hybrid search.
• Infrastructure as Code with Terraform or Pulumi; Kubernetes at production scale.
• LLM eval frameworks (Ragas, DeepEval, Langfuse evals) and offline eval pipelines.
• gRPC for internal service mesh, or GraphQL Federation experience.
• Open-source maintenance, conference talks, or written technical content.

HR Screening Questions (Yes / No)

Use this checklist on the first HR call (15 to 20 minutes). A candidate must answer Yes to at least 7 out of 9 questions to move to the technical screening round. AI experience is not screened at this stage; it is a preferred qualification.

• 1 Do you have 5 to 9 years of backend or full-stack web development experience? Yes / No
• 2 Have you owned at least one production application end-to-end (architecture, build, deploy, operate)? Yes / No
• 3 Are you fluent in Node.js, TypeScript, and modern API design (REST, plus at least one of GraphQL or gRPC) at a production level? Yes / No
• 4 Have you designed PostgreSQL and MongoDB schemas for production workloads? Yes / No
• 5 Have you used Redis in production for caching, sessions, rate limiting, or distributed locks? Yes / No
• 6 Have you used a message queue (RabbitMQ, BullMQ, Kafka, or AWS SQS) for async or long-running workloads in production? Yes / No
• 7 Have you implemented Pub/Sub or WebSocket / Server-Sent Events for real-time updates in production? Yes / No
• 8 Have you mentored or led other developers and led client-facing technical discussions? Yes / No
• 9 Are you able to work full-time from our Kolkata office, and is the senior salary band acceptable? Yes / No