Senior Backend Engineer (Java, Kafka Streams, AWS)
Yard Corporate
Senior / Staff Backend Engineer (Java, Kafka Streams, AWS)
Location: Kraków, hybrid
Contract: B2B or UoP
B2B budget: up to 210 PLN/h + VAT
Work model: around 3 days per week from the office
We are looking for a Senior or Staff Backend Engineer to join a small, high-impact engineering team building a large-scale, event-driven platform.
This is a hands-on role for someone who enjoys working close to real production systems: high-volume data flows, asynchronous processing, external integrations, reliability, observability and technical ownership.
You will join a team where the codebase and domain are evolving, so this is a good opportunity for an engineer who does not need every problem to be fully defined before getting started. You will be expected to investigate, create structure, improve standards and make pragmatic technical decisions.
What you will do
Build and evolve backend services using Java and Spring Boot
Design and maintain real-time event-processing flows using Kafka Streams
Work with stream-processing concepts such as topologies, transformations, joins, aggregations, stateful processing and data routing
Integrate external systems and infrastructure into a scalable internal platform
Improve reliability, observability and production readiness of services handling high-volume data
Investigate production issues, performance bottlenecks and data-flow problems
Work with AWS, Kubernetes, PostgreSQL, MongoDB, Redis, Terraform and Helm
Contribute to code reviews, architecture decisions, documentation and engineering standards
Collaborate with product, platform and engineering stakeholders across an international environment
What we are looking for
7+ years of backend engineering experience
Strong, current hands-on experience with Java and Spring Boot
Deep practical experience with Kafka Streams in production
This should go beyond Kafka producers/consumers and include work with stream-processing logic, joins, aggregations, windowing, state stores or topology design
Background in event-driven, distributed or real-time systems
Hands-on AWS experience, ideally with services such as EKS, S3, SQS, SNS, Kinesis or Lambda
Experience with Kubernetes, containers and production deployment environments
Good understanding of databases such as PostgreSQL, MongoDB and Redis
Strong production mindset: monitoring, debugging, reliability, performance and incident investigation
Ability to work independently in an evolving and not always fully documented technical environment
Clear English communication skills and confidence explaining technical topics to both engineers and non-technical stakeholders
Nice to have
Kotlin experience
Experience with high-throughput data processing or streaming platforms
Terraform, Helm, Prometheus, Grafana, Micrometer or similar observability tooling
Experience in a small product team, scale-up or ownership-heavy engineering environment
Familiarity with AI-assisted development tools
What you can expect
A technically challenging role focused on real production systems rather than isolated feature delivery
Strong ownership
Small team setup with room to influence architecture, standards and ways of working
International engineering environment
Clear recruitment process focused on practical engineering discussions
Recruitment process
Introductory conversation with the Hiring Manager
Technical interview focused on Kafka/use cases and Java/code quality
Final discussion with senior technical leadership
The full company and product context will be shared during the first recruiter call.