Senior Backend Engineer (Polyglot Engineer)

Senior Backend Engineer (Polyglot engineer) Join a global e-commerce technology organisation serving millions of customers across multiple international markets. We're looking for a Senior Backend Engineer who enjoys solving real-world business problems, not just writing code. You'll work on systems responsible for delivery execution, shipment tracking, carrier integrations, and operational visibility across multiple countries and logistics partners. This role is ideal for someone who thrives in ambiguity, enjoys collaborating with stakeholders, and takes ownership from problem discovery through production delivery. What You'll Do Design, build, and scale distributed backend systems. Work with event-driven architectures and messaging technologies. Integrate with external vendors and logistics providers. Collaborate directly with product, operations, and business teams. Drive solutions from idea to production, taking full ownership along the way. Use modern AI tools to improve engineering productivity and software delivery. What We're Looking For 5+ years of backend engineering experience. We value engineers who are language-agnostic and comfortable working across different technology stacks. While Go is our primary language, we welcome candidates with strong experience in Java, Kotlin, Python, or other backend technologies who are excited to learn new tools and choose the right technology for the problem. Strong understanding of microservices, distributed systems, and software architecture. Experience with Kafka, RabbitMQ, SNS/SQS, or similar messaging technologies. Comfortable working with stakeholders and translating business needs into technical solutions. Strong ownership mindset and ability to work with incomplete requirements. Experience using AI coding tools such as Cursor, Claude Code, Copilot, or similar. Nice to Have Experience in logistics, supply chain, operations, or fulfilment domains. Experience integrating third-party systems and vendors. Startup or scale-up background. Additional European languages. What We Offer Build systems used by millions of customers globally. Real ownership and influence over technical decisions. Highly autonomous and product-focused engineering culture. International environment and global collaboration. Hybrid working model (3 days per week in the Warsaw office). B2B cooperation model. 30 days of paid annual leave.