Backend Engineer (Java/Kotlin)

Quick Facts

• Backend Engineer role focused on high-performance e-commerce and payment systems (20,000+ RPS)
• Remote work preferred, with occasional presence in Warsaw or Poznań (2 times per quarter)

Description

You will develop advanced payment systems and large-scale e-commerce backend solutions in an Agile environment where performance, reliability, security, and low latency are critical. The role combines backend development with active participation in system architecture design, technical decision-making, and solving complex business problems.

Responsibilities

• Design, develop, and optimize high-performance microservices using Java/Kotlin and Spring Boot
• Evolve the architecture of payment systems and integrate new payment methods
• Design authorization and transaction security mechanisms, including multi-factor authentication and biometrics
• Participate in critical data migrations and integrations with cloud services
• Build support for international transactions, currency conversion, and financial reconciliation
• Ensure high availability, scalability, and fault tolerance of systems
• Monitor application performance, define metrics, and optimize deployment processes
• Own the full service lifecycle—from requirements analysis through production deployment and maintenance (including on-call)

Requirements

• Very good knowledge of Java or Kotlin and Spring / Spring Boot
• Experience designing and developing microservices architecture
• Practical knowledge of distributed systems, asynchronous processing, and performance optimization
• Experience with databases, especially MongoDB
• Knowledge of service-to-service communication, REST API, and Apache Kafka
• Experience designing failure-tolerant solutions (e.g., Circuit Breaker, Rate Limiter)
• Experience monitoring production systems and analyzing metrics
• Ability to make technical decisions independently and take ownership of delivered solutions
• Collaboration with technical and business teams and English communication skills

Benefits

• Support for professional and personal development
• Individual support from a Service Delivery Manager to plan your career path and ensure work satisfaction
• Training, certificates, and conference funding/coverage for technical skills development
• #SmartChange — possibility to switch projects based on your preferences
• Work-life balance support: integration events, sports activities, and #edge1talks webinars
• Health package: private care, sports card, insurance, and a platform with psychological support
• Flexible benefits: choose how to spend benefit points