Senior Staff Software Engineer

Kontakt.io; Kraków; On-site; PLN 212,404 - 297,366; Full time

Benefits offered by this job

Equity in Series C company

Private healthcare

Multisport card

Competitive salary

Job summary

Kontakt.io, based in Kraków, is seeking an experienced backend engineer with extensive knowledge of Java and Kafka. You will design and maintain integration systems that handle real-time BLE and IoT data while ensuring top-level performance and documentation standards.

This role requires substantial backend experience, strong collaboration skills, and the ability to maintain high engineering standards in a dynamic environment, integrated within a tech-oriented culture. A competitive salary and stock options are part of the offer.

Qualifications

• 7+ years of backend software engineering experience, especially with Java and Spring Boot.
• Deep understanding of Apache Kafka operation and design principles.
• Experience in developing real-time, event-driven systems in a SaaS environment.

Responsibilities

• Design and maintain services that process real-time BLE and IoT telemetry.
• Build and maintain integrations with third-party systems.
• Drive architectural decisions and enforce documentation standards.

Skills

Backend software engineering

Java (Spring Boot)

Apache Kafka

Database fluency (MongoDB, PostgreSQL, Redis)

AWS experience (EKS, Kinesis, S3)

English communication

Tools

Terraform

Helm

Testcontainers

Job description

About Kontakt.io

Kontakt.io is building the platform that care operations run on. We reduce waste, cut costs, and improve throughput in hospitals by automating and orchestrating clinical workflows. Using AI, real-time location data (RTLS), and deep EHR integration, our platform enables care teams to operate with real-time intelligence and financial discipline.

Trusted by leading U.S. health systems including HCA, Sutter Health, AdventHealth, Trinity Health, and the U.S. Department of Veterans Affairs — and backed by Goldman Sachs — we are scaling rapidly toward the next phase of durable, disciplined hypergrowth.

Kontakt.io is the leading IoT platform for real-time location and telemetry in healthcare and enterprise. Our systems monitor hundreds of thousands of assets and people across hospitals and campuses globally — processing billions of BLE events daily through a Kafka-first, cloud-native architecture.

The 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.

Day-to-day Responsibilities

• 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

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.

We Offer

• Competitive salary reflecting staff-level seniority — we benchmark against market
• Equity in a Series C company with a clear growth trajectory
• Private healthcare, Multisport card, and standard benefits package
• Hybrid from Kraków office - at least 2 days in the office
• A real technical challenge — not a maintenance role on a stable codebase