Karol Nowacki
@karolnowacki
Senior Java Developer at IG Group, modernizing trading middleware and upgrading services to Spring Boot 4 and Java 21.
PolandWhat I'm looking for
At IG Group, I build and run trading middleware on Spring Boot, Kafka and ActiveMQ. I migrated two business-critical reporting services from VMs to Docker on Nomad and upgraded four services to Spring Boot 4 and Java 21.
At Mapp Digital, I designed the Mapp Connect backend from scratch and led a four-person team while staying hands-on. I’ve also built and supported Java services at Tesco Technology and Satago, and I’m the author of ptys + choux, open-source tools for persistent terminal sessions.
Experience
Work history, roles, and key accomplishments
Senior Developer
IG Group
Apr 2026 - Present (5 months)
Migrated two business-critical reporting services from CentOS 7 VMs to Docker on Nomad and upgraded four services from Spring Boot 2.7 and Java 17 to Spring Boot 4 and Java 21. Diagnosed and fixed production incidents, retired legacy services, and published C4 architecture documentation.
Software Engineer
Tesco Technology
Aug 2024 - Mar 2026 (1 year 7 months)
Built and ran Java 21 backend services on Azure for the colleague rewards and benefits platform. Migrated leader election from ZooKeeper to PostgreSQL and owned features end to end, from API design to production release.
Implemented the backend of the Sage Intacct integration for Satago Cash Flow Management. Developed Java backend on AWS for the cash flow management and invoice finance platform.
Team Lead Software Engineering
Mapp Digital
Mar 2016 - May 2023 (7 years 2 months)
Designed the Mapp Connect backend from scratch, including Java microservices, Apache Flink processors, Kafka messaging, and CouchDB configuration. Led a four-person engineering team while remaining hands-on in development, architecture, and operations.
Designed, implemented, and supported Dell TPAM privileged access management, and supported identity management and LDAP platforms. Served as Restricted Security Officer for ING, handling Unix account management and security guidelines.
Education
Degrees, certifications, and relevant coursework
Cracow University of Technology
Bachelor of Engineering, Computer Science
Bachelor of Engineering in Computer Science, completed in 2025.
Red Hat
Red Hat Certified Engineer (RHCE) and Red Hat Certified System Administrator (RHCSA), System Administration
Earned Red Hat Certified Engineer (RHCE) and Red Hat Certified System Administrator (RHCSA) certifications in 2014.
EXIN
ITIL Foundation, IT Service Management
Earned ITIL Foundation certification from EXIN.
Tech stack
Software and tools used professionally
Availability
Location
PolandAuthorized to work in
Portfolio
github.com/pty-serverSalary expectations
Social media
Job categories
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