Senior or Mid Backend Software Engineer (m/f/d)

We build modern, highly-scalable fintech platform for both traditional and crypto trading. Clean code and clear processes are baked into our culture. With production customers already live and usage growing fast, we’re expanding the platform team with a Mid-Level Back-End Engineer who can ship reliable services today and help us scale for tomorrow.

We're seeking skilled and motivated Backen Software Engineers to join our team in Warsaw.

Location: Hybrid (Warsaw – in-office every Tuesday & Thursday)

Your day-to-day

• Implement new micro-services and extend existing ones in Go.
• Help groom user-story requirements and surface performance / scaling concerns early.
• Write unit, integration and API tests; review PRs.
• Tune data-models in DynamoDB & Postgres for low-latency, high-throughput workloads.
• Pair with DevOps on CI/CD and observability improvements.
• Participate in on-call rotation as we’re building high available fintech system

Additional tasks of the Senior

• Design and drive high-scale, low-latency services (tens of thousands of orders / sec).
• Lead architecture reviews, challenge assumptions and keep tech debt in check.
• Partner with Product on roadmap feasibility & effort sizing.
• Be a mentor to less experienced colleagues

Perfect candidate profile

• ~3 years of professional back-end experience (ideally 1 year+ in Go).
• Solid grasp of cloud-native design (RESTful APIs, event-driven patterns).
• Working SQL and NoSQL skills; know when each shines.
• Comfort diagnosing performance bottlenecks in distributed systems.
• Ability to work on-site in Warsaw twice a week (Tue & Thu) and remotely otherwise.

Nice to have

• Exposure to serverless architectures on AWS.
• Experience with Kafka or another high-volume message bus.
• Knowledge of automated trading, market data, or FIX/crypto exchanges.
• Familiarity with Infrastructure-as-Code (Terraform or CDK).

What we offer

• An experienced, welcoming team that loves clean, well-tested code.
• Real impact: the features you ship go straight into production for live traders.
• Flexible hours, modern tooling, and a fintech domain that’s never boring.
• Occasional work travel to Germany (Munich / Berlin)
• 20 days PTO on B2B
• Multisport card