Senior Software Engineer (Backend, C#)

Quick Facts

• Role: Senior Software Engineer (Backend, C#)

Description

You will own an end-to-end technical area for Xopero ONE or GitProtect—from architecture and implementation through production reliability. You will design solutions based on real customer/user needs, diagnose and solve production issues (performance, memory, I/O, concurrency), and improve stability, performance, and observability. The role also includes mentoring, code/design reviews, and responsible use of AI-assisted development.

Responsibilities

• Deliver features end-to-end for Xopero ONE or GitProtect: architecture decisions, implementation, and production operation

• Analyze user/customer problems and challenge requirements when needed

• Make and justify technical decisions with awareness of performance, cost, complexity, delivery time, and tech debt

• Add support for new backup sources, restore flows, and integrations; assess technical feasibility and risk

• Diagnose and systematically fix production issues (performance, memory, I/O, concurrency, reliability)

• Improve stability, performance, and observability (metrics, logging, tracing, alerting, runbooks)

• Evolve existing codebases while paying down technical debt

• Prepare the area for future on-call/application duty using metrics, logs, tracing, alerting, and runbooks

• Conduct code review and design review; mentor less experienced engineers

• Contribute to and enforce software engineering standards to ensure readiness for release

• Use AI tools in daily development while verifying outputs and owning final code quality

Requirements

• Minimum 5 years of commercial experience building and maintaining products in statically typed languages (e.g., C#, .NET, Java, Go, C++, Rust, Kotlin)

• Production experience with systems running longer than one year and ability to assess long-term correctness of technical choices

• Ability to diagnose production problems and analyze root causes, including performance, memory, I/O, and concurrency

• Ability to design solutions using trade-offs between performance, cost, complexity, and time

• Experience with containerized and orchestrated applications (e.g., Kubernetes)

• Experience with SQL and NoSQL databases: modeling, query optimization, and data migrations

• Working knowledge of Windows and Linux for diagnosing application behavior

• Ability to work with legacy code and improve it incrementally

• Observability as part of design (metrics/logs/traces needed for production)

• Experience with unit and integration testing

• Strong Git skills and experience with trunk/feature flow

• Experience with AI-assisted development tools and critical evaluation of generated code

• Ability to own results

Benefits

• Employment: UoP or B2B

• Compensation: UoP 19,900–24,900 PLN gross; B2B 142–179 PLN/hour net + VAT

• Full-time role

• Hybrid work: 3 remote days + 2 days in offices (Gorzów Wielkopolski, Warsaw, Sopot, Kraków, Bielsko-Biała, or Szczecinek)

• Work language: Polish and English

• 26 days paid service suspension (B2B)

• Necessary tools and equipment from day one

• Employee referral program

• Training budget and free English lessons

• Knowledge exchange with cybersecurity, backup, and SaaS experts; participation in globally developed projects

• Private medical care (Luxmed package from 1 PLN), Multisport co-financing, an extra health-focused day, life insurance co-financing

• Welcome pack, annual employee awards gala, integration events, holiday gifts, and childcare starter kit