OnHires
Senior Fullstack (Node.js + React.js)
OnHiresPoland4 hours ago
Full-timeRemote FriendlyEngineering

Location: Warsaw, Poland (Hybrid — 2–3 days/week in the office)

Employment: Full-time, B2B contract

Language: English


About the Company

The hiring company is an independent product-based SaaS organization with a portfolio of 10+ in-house B2C digital products. The company builds and scales its own products - no outsourcing, no external clients, and no investor pressure. The engineering function operates in a hybrid model in Warsaw, where collaboration 2–3 days per week in the office is required.

About the Role

The company is seeking a Senior SDE Fullstack who will take full hands-on ownership of backend and frontend feature development, contribute to architecture decisions, ensure performance, and maintain code quality across a modern SaaS environment.

This is a senior individual contributor role, fully hands-on - without people-management responsibilities.


What You’ll Do

Hands-On Engineering (Backend & Frontend)

  • Build and deliver complex features end-to-end using Node.js, NestJS, React.js, Next.js, TypeScript.
  • Design and implement scalable backend services and secure REST APIs.
  • Develop performant frontend components, SSR flows, routing, and state management.
  • Write clean, maintainable, well-tested code.
  • Participate in architectural discussions within the product team.

Performance, Reliability & Observability

  • Implement and refine logging, monitoring, and alerting (Sentry, Datadog, Groundcover).
  • Troubleshoot and optimize backend and frontend performance.
  • Participate in incident resolution and root-cause analysis.
  • Improve system reliability, traceability, and error visibility.

CI/CD, Git & DevOps Collaboration

  • Maintain and enhance CI/CD pipelines (including GitHub Actions).
  • Work with DevOps to ensure consistent and stable environments across dev/staging/production.
  • Manage and contribute to Git branching strategies (Git Flow or Trunk-Based Development).
  • Ensure smooth, efficient, predictable deployment workflows.


Tech Stack Requirements

Must-Have

  • 5+ years of professional full-stack engineering experience
  • Strong production experience with:
  • Node.js, NestJS
  • React.js, Next.js
  • TypeScript
  • Solid PostgreSQL knowledge (data modeling, optimization, indexing)
  • Strong experience with AWS services (Lambda, S3, CloudWatch, SNS/SQS or equivalents)
  • Experience building secure REST APIs (JWT auth, security best practices)
  • Understanding scalable architectures and distributed systems basics
  • Hands-on experience with CI/CD pipelines and GitHub Actions
  • Docker experience
  • Experience managing Git branching strategies (Git Flow / Trunk-Based Development)
  • Ability to work hybrid in Warsaw (2–3 days/week in the office)


Nice-to-Have (Strong Plus)

  • Kubernetes (K8s)
  • ArgoCD or GitOps workflows
  • Event-driven systems (Kafka, RabbitMQ, AWS SNS/SQS)
  • Infrastructure as Code (Terraform)
  • Observability tooling (Sentry, Datadog, Groundcover)
  • Experience with design systems / Storybook
  • Experience with internal utilities or shared packages
  • Experience with test automation frameworks (Playwright or similar)


Key Performance Indicators (KPIs)

  • Reliable end-to-end feature delivery
  • Architecture clarity and maintainability
  • Production stability & incident resolution speed
  • CI/CD stability and deployment quality
  • Code quality, documentation, and testing discipline


What the Company Offers

  • Competitive compensation
  • 22 paid vacation days + national holidays
  • Annual learning & development budget (courses, certifications, conferences)
  • Opportunity to contribute to a fast-growing multi-product SaaS environment
  • Modern technology stack with minimal legacy
  • Hybrid work model with a Warsaw-based office
  • Senior, autonomous engineering culture focused on product impact


Interview Process

  1. External recruiter call (30 min) – introduction, expectations
  2. Recruiter Interview (prescreen, scorecard, expectations)
  3. Technical Interview with Thomas Goik
  4. SDE Challenge
  • 1-day test assignment
  • Must be submitted within 5 days
  1. Second Technical Interview with Ionel & Dima
  2. HR Interview (Professional skills, ways of working, cultural philosophy)

Key Skills

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