N-iX
Senior Node.JS Engineer (Nest.JS)
N-iXUkraine9 hours ago
ContractRemote FriendlyEngineering
Our client is one of Europe's fastest-growing mobile companies with 5 million active customers, 1,000 employees worldwide, and operations in five countries. The client is using the mobile virtual network operator business model.

We are looking for a Senior Backend result-oriented developer who has good knowledge and experience of Nest.js.

Responsibilities:

  • Own microservices in NestJS (TypeScript): define module boundaries, version APIs, and ship resilient, well-tested services.
  • Design internal communication: implement REST/gRPC/event-driven patterns (e.g., request/response, pub/sub), handle retries, timeouts, backoff, and circuit breakers.
  • Implement secure JWT auth: access/refresh lifecycles, rotation, audience/issuer validation, revocation/blacklisting, and token storage best practices.
  • Deliver payment integrations: integrate with gateways (e.g., Stripe/Adyen/Braintree), implement idempotent operations, handle captures/refunds/disputes, and reconcile via signed webhooks.
  • Build and consume webhooks: define payload contracts, verify signatures/HMAC, ensure idempotency, and implement robust retry and DLQ strategies.
  • Enable real-time features with WebSockets: use NestJS Gateways/Socket.IO or ws for presence, notifications, and fan-out at scale; secure and rate-limit connections.
  • Use Redis/Valkey effectively: design cache keys/TTLs, apply cache-aside/write-through, implement distributed locks, queues/streams, pub/sub, and mitigate hot keys.
  • Containerize and run locally: craft efficient multi-stage Docker builds, add healthchecks, and orchestrate multi-service dev stacks with docker-compose.
  • Quality & reliability: write unit/integration/e2e tests (Jest/Supertest), add schema validation (class-validator/OpenAPI), and instrument with logs/metrics/traces.
  • Collaborate across teams: review PRs, write concise design docs, and partner with product, frontend, and data to deliver measurable outcomes.

Requirements:

  • 5+ years building backend systems; 3+ years NestJS + TypeScript in production.
  • Strong Docker and docker-compose skills (multi-stage builds, image slimming, healthchecks).
  • Solid microservice design: domain boundaries, API versioning, idempotency, saga/choreography, and eventual consistency (outbox/inbox).
  • Hands-on JWT implementation in distributed systems.
  • Demonstrated payment experience (idempotency keys, reconciliation jobs) and webhooks (HMAC/signatures, replay protection, retries).
  • Built and scaled WebSockets features in production.
  • Proficiency with Redis/Valkey for caching and real-time patterns; strong SQL fundamentals (PostgreSQL/MySQL) and practical ORM experience (TypeORM/Prisma).
  • Testing mindset with meaningful coverage and CI checks; working knowledge of security best practices (OWASP, secrets management, least privilege).
  • Comfortable with telemetry (structured logs, metrics, tracing) and on-call ownership.

Nice to have:

  • Kong Gateway (or similar API gateway) for routing, auth, rate limiting, and observability.
  • Kubernetes/Helm; service meshes (Istio/Linkerd).
  • Event platforms (NATS/Kafka/RabbitMQ) and streaming patterns.
  • GraphQL (Apollo/NestJS) including subscriptions.

We offer*:

  • Flexible working format - remote, office-based or flexible
  • A competitive salary and good compensation package
  • Personalized career growth
  • Professional development tools (mentorship program, tech talks and trainings, centers of excellence, and more)
  • Active tech communities with regular knowledge sharing
  • Education reimbursement
  • Memorable anniversary presents
  • Corporate events and team buildings
  • Other location-specific benefits
  • not applicable for freelancers

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