Principal Engineer: Architecture & Backend Modernization

ABC Fitness; Poland; On-site; PLN 460,000 - 470,000; Full time

Benefits offered by this job

Open PTO

Days of Disconnect

Parental Leave

Fitness Reimbursement

Discounts

Medical/Dental/Vision coverage

EAP

Calm App +4

Job summary

ABC Fitness is seeking a Principal Engineer in Poland to lead modernization of critical software while staying hands-on in implementation. You’ll shape architecture, domains, APIs, and data flows across Java/Springboot, Golang, Node/TypeScript ecosystems, balancing long-term quality with release velocity.

You’ll guide upgrades, optimize concurrency and reliability, and collaborate across teams to deliver durable software that supports business continuity and scale.

Qualifications

• Extensive experience designing, building, operating, and evolving production backend systems.
• Ability to move from architecture into code, configuration, instrumentation and diagnosis.
• Strong judgment for service boundaries, migration strategies and integration patterns.

Responsibilities

• Lead software architecture and modernization.
• Stay deeply hands-on in code across backend ecosystems.
• Design domain models and APIs with clear ownership and service contracts.
• Modernize foundations, upgrade frameworks, and improve deployment readiness.
• Ensure correctness, performance, reliability, and robust data access.
• Improve data integration, caching, messaging, and event patterns.
• Raise code quality with strong testing, reviews, and tooling.

Skills

Backend engineering

Distributed systems

Java/Springboot

Golang

Node/TypeScript

Tools

Oracle

Kafka

Job description

ABC Fitness is seeking a Principal Engineer in Poland to lead modernization of critical software while staying hands-on in implementation. You’ll shape architecture, domains, APIs, and data flows across Java/Springboot, Golang, Node/TypeScript ecosystems, balancing long-term quality with release velocity.

You’ll guide upgrades, optimize concurrency and reliability, and collaborate across teams to deliver durable software that supports business continuity and scale.