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.

GB2B-GamingB2B
- Powering the Next Generation of iGaming Platforms - GB2B is a global B2B technology company providing infrastructure and development solutions for the online gaming industry. We play an active role in the creation and ...
Senior Backend Developer (Nest.js / Express.js)
Senior Backend Developer (Nest.js / Express.js)