Senior Backend Python Engineer (Core Gateway)

The role is about: We are expanding our engineering capabilities and looking for a Senior Backend Developer to join our Core Gateway team. This is a unique, dual-track role where you will play a central part in both the present and future of our infrastructure. You will support, maintain, and extend our existing Perl-based payment gateway ensuring stability and high performance in a live financial production environment while simultaneously leading the architecting and building of our next-generation Python microservices platform. In this role, you will work in a fast-paced environment where system performance, scalability, and 99.9% reliability are critical to our core transaction flow. Location: Remote from Poland (Contractor arrangement) or Cyprus Onsite (employment arrangement) Reporting to: Technical Lead What you will do: Dual-Track Maintenance: Support and extend the existing Perl-based payment gateway debugging production issues and adding features while the migration is ongoing. Modernization: Design, develop, and maintain modern server-side components in Python, ensuring high performance and scalability. Integrations: Integrate third-party APIs and external payment services into both legacy and modern platform layers. Agile Collaboration: Maintain clean and strong English communication to effectively collaborate with multiple stakeholders across departments working in agile sprints. Product Thinking: Go beyond the "what" and "how" of the code bring a product-focused mindset to understand the business logic and user impact of what you build. Engineering Standards: Participate in code reviews, uphold high code quality standards, and contribute to a culture of continuous improvement. Infrastructure: Work closely with DevOps on CI/CD pipelines, containerization, and cloud deployments. What we need: Python Expertise: 5+ years of backend engineering experience with strong Python mastery (AsyncIO and FastAPI preferred). Legacy Flexibility: Experience with Perl (or a genuine eagerness to learn and work within Perl production code). We value polyglot engineers who can read and refactor legacy code. API Mastery: Solid experience integrating third-party APIs and a deep understanding of webhooks, callbacks, and retry policies. Tech Stack: Experience with CI/CD pipelines (GitLab preferred), Docker containerization, and familiarity with AWS (Lambda, cloud services). Architecture: Exposure to event-driven architectures (Kafka, message queues, etc.). Clean & Intentional Code: We value deep engineering logic over AI-generated snippets. You should be a "clean code" advocate who can explain the reasoning behind every line you ship. Curiosity for Product: You care about the "why" behind a feature. You are interested in how a product works for the end-user and the business. English Proficiency: Strong English communication skills—both written and verbal—to collaborate across multi-functional teams. Hiring Process: Step 1 –…