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

Tech stack you’ll work with Core: Golang, AWS Serverless (Lambda, API Gateway, SQS) Data: DynamoDB, PostgreSQL Messaging: Kafka Ops / Tooling: Terraform, Guthub Actions (CI/CD) (If you haven’t touched every tool yet, no worries — we’ll get you up to speed.) Your role Your mission and responsibilities Mid Backend Software Engineer 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 Your qualifications and experience 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). Contract B2B / Employment contract Location Hybrid (Warsaw – in-office every Tuesday & Thursday) Why us? 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 Apply now! Apply now!