Principal Engineer – Software Architecture and Modernization-2

Location: Remote in Poland

Salary: PLN 460,000–470,000 annually

Company

Provides scalable, data-driven software for fitness businesses, supporting club management, member engagement, and payment processing.

What you will do

• Lead the architecture and hands-on modernization of legacy, database-centric applications into domain-oriented software.
• Define service boundaries, domain models, APIs, migration seams, compatibility strategies, and incremental implementation plans.
• Contribute directly to backend implementation, prototypes, refactoring, code reviews, production fixes, and framework or runtime upgrades.
• Improve correctness, performance, concurrency, recovery behavior, data access, caching, messaging, and event-consumer patterns.
• Establish reusable engineering patterns, reference implementations, architecture decisions, testing practices, and code-quality standards.
• Partner with engineering, product, security, and data teams to turn technical strategy into executable cross-team work.

Requirements

• Substantial experience designing, building, operating, and evolving production backend systems, APIs, and distributed applications.
• Hands-on implementation experience with backend ecosystems such as Java/Spring Boot, Golang, Node, or TypeScript.
• Strong knowledge of domain modeling, service transformation, modular design, incremental refactoring, and architecture for complex existing systems.
• Experience with relational databases, SQL behavior, messaging, event consumers, data movement, caching, and legacy data dependencies.
• Expertise in production reliability, performance diagnosis, concurrency, dependency flows, automated testing, code review, static analysis, and secure coding.
• Ability to provide principal-level technical leadership without direct people management and to use AI-assisted engineering across code comprehension, implementation, testing, debugging, and modernization.

Nice to have

• Experience modernizing large systems, upgrading frameworks and runtimes, decomposing monoliths, or extracting services.
• Experience with Oracle, Kafka, complex data migrations, reporting dependencies, profiling, runtime instrumentation, or concurrency analysis.
• Experience applying AI coding agents to codebase analysis, implementation, testing, and software modernization.

Culture & Benefits

• Values-focused culture built around Best Life, One Team, and Growth Mindset.
• Remote work arrangement with an open PTO policy and quarterly company-wide Days of Disconnect.
• Parental and pet-parent leave, quarterly fitness reimbursement, partner discounts, and Calm App access.
• Medical, dental, and vision coverage, plus an employee assistance program.
• Additional compensation may include bonuses, commissions, equity, or other incentive programs where applicable.