Senior Backend Engineer - Domain & Onboarding Systems

JustBacked; Warszawa; On-site; PLN 180,000 - 300,000; Full time

Job summary

AppsFlyer is seeking an exceptional Backend Software Engineer to join the Domain Team within SaaSLab. You will design, build, and operate backend systems powering accounts, apps, and users, with a focus on scalable data flows and onboarding experiences.

The role demands ownership from design through production in a distributed, cloud-based environment. As part of SaaSLab, you will collaborate across teams to evolve the domain model, adopt GraphQL Federation, and ensure high availability and

Qualifications

• 5+ years of software development experience expected.
• Experience building and operating production-grade distributed systems.
• Strong understanding of design, architecture and best practices.
• Experience with high-scale, cloud-based architectures.
• Ability to own problems from design to production.
• Excellent collaboration and communication across teams.
• Proficiency in written and verbal English.
• B.Sc. in Computer Science or equivalent practical experience.

Responsibilities

• Design, develop, and maintain scalable backend systems and data flows for core entities and onboarding.
• Decouple from legacy data stores and adopt modern patterns like GraphQL Federation.
• Write high-quality, thoroughly tested production code; own features end-to-end.
• Engage in architecture reviews and code reviews to raise the bar.
• Collaborate with product managers, team leads, and engineers to deliver roadmaps.
• Ensure high availability, security, and operational excellence for critical services.
• Troubleshoot production issues and contribute to on-call rotations.
• Stay curious about new tools and AI-powered SDLC practices.

Skills

Backend engineering

Distributed systems

Cloud architecture

English proficiency

Ownership mindset

Education

B.Sc. in Computer Science or equivalent

Tools

Node.js

GraphQL

Neo4j

Kafka

Redis

AWS

Job description

AppsFlyer is seeking an exceptional Backend Software Engineer to join the Domain Team within SaaSLab. You will design, build, and operate backend systems powering accounts, apps, and users, with a focus on scalable data flows and onboarding experiences.

The role demands ownership from design through production in a distributed, cloud-based environment. As part of SaaSLab, you will collaborate across teams to evolve the domain model, adopt GraphQL Federation, and ensure high availability and