Senior Backend Developer (Nest.js / Express.js)

Senior Backend Developer (Nest.js / Express.js)

Location: Warsaw (On-site)

Company: GB2B

Industry: iGaming / Platform Development

GB2B empowers iGaming companies to deliver seamless player experiences and operate with absolute confidence. As we continue to scale and build the next generation of high-performance platform technologies, we’re looking for a Senior Backend Developer to join our mission.

We offer flexibility in contract type and can proceed either with a B2B agreement or a standard employment contract, depending on your preference.

Responsibilities

● Build, maintain, and optimize backend services using Node.js (Nest.js / Express.js)

● Improve existing systems, resolve complex issues, and contribute to new high-performance platform features

● Design and implement scalable architectures for high-traffic, distributed environments

● Work with PostgreSQL and MongoDB, ensuring performance, optimization, and data integrity

● Manage and deploy cloud-based architectures (AWS / GCP / Azure)

● Work with Dockerized services, ensuring backend applications are compatible with containerized environments and integrate smoothly with existing CI/CD and deployment pipelines.

● Collaborate closely with cross-functional teams to deliver secure, reliable, and maintainable solutions

● Apply best practices for data privacy, security, and high-availability services

● Participate in technical and architectural discussions, helping evaluate trade-offs between system performance, reliability, scalability, and business needs

Requirements

● 5+ years of experience building backend systems with Node.js, using Nest.js or Express.js

● Strong expertise with PostgreSQL, MongoDB, and cloud database environments

● Proven experience with high-traffic, large-scale, and complex system architectures

● Hands-on experience with Docker, load balancing, and performance scaling strategies

● Solid understanding of system design, data structures, and cloud infrastructure

● Familiarity with security standards and data protection principles

● Demonstrated platform and product mindset — ability to assess technical decisions in the context of reliability, scalability, user impact, and business constraints

● Excellent problem-solving skills with a proactive, solution-oriented approach

● Strong communication skills and ability to collaborate effectively within cross-functional teams

Why Join GB2B

● Be part of an innovative team shaping the future of the iGaming industry

● Work on meaningful, high-impact projects at global scale

● Competitive, rewarding compensation package

If building reliable, scalable backend systems motivates you, we’d love to meet you.