Staff Software Engineer

O projekcie: Our team is the connective tissue of this platform. We own the full data ingress pipeline — from third-party devices (Cisco, Aruba, and beyond) to our internal Kafka backbone — and we own egress: streaming enriched location and telemetry data out to downstream systems, external APIs, and partner platforms. We are rebuilding this domain the right way: event-driven, observable, documented, and built to scale. We need a technical anchor — someone senior enough to raise the bar, pragmatic enough to ship, and confident enough to drive alignment across engineering and product. What you will work on: Data ingress & device integration Own the pipeline that brings external device data into the Kontakt.io platform. Build and maintain robust integrations with Cisco Spaces, Aruba, and similar third-party infrastructure. High-volume BLE telemetry, Kafka Streams, gRPC — multi-tenant SaaS where both correctness and latency matter. Data egress & external integrations Build and evolve the egress layer that streams enriched location and event data to partner systems and customer-facing APIs — real-time position feeds, alarm forwarding, standards-compliant adapters. You own how the outside world consumes Kontakt.io data. Architecture & technical leadership You will drive the architectural evolution: what to rewrite, what to stabilize, and how to sequence it without breaking production. You establish the engineering standards — documentation, testing with Testcontainers, observability with Prometheus/Grafana — and you hold the team to them. Cross-team ownership Work directly with product stakeholders to translate business requirements into engineering decisions. When scope is unclear, you clarify it. When dependencies block the team, you resolve them. Wymagania: What we are looking for: - 7+ years of backend software engineering, with strong production Java experience — Spring Boot and ideally Kotlin too- Deep, hands-on Apache Kafka knowledge: Streams, state stores, topology design, and operational behavior — not just produce/consume- Experience building real-time, event-driven distributed systems in multi-tenant SaaS environments- Solid database fluency: MongoDB, PostgreSQL, Redis — you know when to use what and why- Hands-on AWS experience: EKS, Kinesis, S3; comfortable reading and writing Terraform and Helm- Track record of taking ownership of a messy, under-documented domain and making it better- Ability to work directly with product and business stakeholders — you can translate between engineering and everything else- Clear written and verbal English; the team is international- Based in or willing to relocate to Kraków, Poland Nice to have: - Experience with IoT or BLE telemetry systems- Go or Python for tooling and automation- Familiarity with AsyncAPI, Drools rules engine, or OAuth2/Keycloak- Background in a high-growth Series B/C product company The kind of Engineer we are hiring: You should be comfortable with ambiguity, allergic to sloppiness, and capable of holding a high bar while still shipping. If you think AI tools are optional extras rather than a core part of how modern engineers work, this is not the right role. Codzienne zadania: - Design, build, and maintain Java/Spring and Kafka Streams-based services processing real-time BLE and IoT telemetry at scale - Own ingress integrations with third-party location platforms — from protocol understanding to production reliability - Build egress pipelines streaming location and event data to downstream systems via REST, gRPC, and WebSocket - Drive architectural decisions and document them — the team currently operates on verbal agreements; you will change that - Use AI tools as a core part of your development workflow: code generation, debugging, documentation, prototype acceleration - Define and enforce testing standards using Testcontainers and CI pipelines (Jenkins, GitHub Actions) - Instrument services with Prometheus and Micrometer; build Grafana dashboards that give the team real operational visibility - Collaborate with Data Platform and SRE teams on Kafka topology, state store configuration, and infrastructure ownership - Mentor engineers on the team — through code reviews, design sessions, and honest feedback