Principal Engineer: Software Architecture & Modernization (Hands-On)

abcfinancial; Poland; On-site; PLN 320,000 - 560,000; Full time

Job summary

ABC Fitness is seeking a Principal Engineer to lead the architecture and modernization of critical software systems. You will influence across domains while staying close to implementation.

You will work on backend architectures, domain models, APIs, data access, and testing, transforming complex technical risk into durable software. This is a hands-on, individual-contributor role rather than people management.

Qualifications

• Substantial experience designing, building, operating, and evolving production backend systems, services, APIs, and distributed applications.
• Credible hands-on implementation depth across code, prototypes, refactoring, and production fixes.
• Experience with backend ecosystems (e.g., Java/Springboot, Golang, Node/TypeScript) and modern architecture patterns.
• This is a hands-on contributor role, not a people-management or architecture-only position.

Responsibilities

• Lead software architecture and modernization of legacy applications into domain-oriented software.
• Stay deeply hands-on in code, contributing to implementations, prototypes, and production fixes.
• Design strong domain models and APIs to clearly express business rules and service contracts.
• Translate architectural risk into code-level priorities and work with cross-functional teams to deliver.

Skills

Deep backend and distributed-systems

Hands-on implementation depth

Job description

ABC Fitness is seeking a Principal Engineer to lead the architecture and modernization of critical software systems. You will influence across domains while staying close to implementation.

You will work on backend architectures, domain models, APIs, data access, and testing, transforming complex technical risk into durable software. This is a hands-on, individual-contributor role rather than people management.