Senior Backend Software Engineer

Quick Facts

• Role: Senior Backend Software Engineer (Remote contractor from Poland)

• Team focus: Payment gateway projects

• Reporting line: Technical Lead

Description

Join the Gateway Related Projects team to help deliver stable, high-reliability payment processing. You will extend a legacy Perl-based payment gateway while architecting and building scalable Python microservices for production high-load environments. You’ll lead engineering best practices, integrate third-party payment APIs with robust error handling, and maintain production reliability with a zero-downtime mindset.

Responsibilities

• Support and extend the existing Perl-based payment gateway while building high-performance Python microservices

• Architect and implement scalable distributed Python services to replace legacy components

• Integrate and manage third-party APIs and external payment services (webhooks, callbacks, idempotency, retries)

• Lead code reviews, drive best practices, and identify performance/scalability bottlenecks

• Collaborate with DevOps to improve CI/CD pipelines using GitLab and deploy using AWS services (e.g., Lambda, ECS)

• Adopt a product mindset to understand business logic, user impact, and the why behind features

• Troubleshoot and resolve complex production issues in distributed systems with a zero-downtime focus

Requirements

• 5+ years of backend engineering with deep Python expertise (FastAPI and AsyncIO preferred)

• Perl experience is a major plus; willingness to work within Perl production code is required

• Experience scaling microservices and high-throughput systems

• Deep understanding of integrating third-party APIs, especially webhook/callback flows, idempotency, and retry policies

• Strong AWS knowledge (Lambda, SQS/SNS, and cloud networking) and Docker/containerization experience

• Familiarity with event-driven architecture and messaging systems (e.g., Kafka, RabbitMQ)

• Ownership experience from design to production and ability to mentor other engineers

• Strong written and verbal English communication

Benefits

• Annual learning budget for professional development (eligible after probation)

• Company-wide celebrations with colleagues from all offices

• Opportunities to participate in international events and initiatives