Senior Software Engineer

Lumilens; Kraków; On-site; PLN 180,000 - 240,000; Full time

Benefits offered by this job

Competitive salary

Professional development opportunities

Access to cutting-edge technology

Collaborative work environment

Job summary

A technology startup in Kraków seeks a C#/.NET Developer to create advanced manufacturing software for optical transceiver testing. The role requires deep experience in C# and Python, concurrent programming, and the ability to work with manufacturing processes. You'll contribute to a groundbreaking technology venture, leveraging your skills in GUI application development while collaborating with cross-functional teams. Competitive salary and professional growth opportunities are offered.

Qualifications

• 5+ years of experience with C#/.NET, especially in GUI applications.
• Strong command of concurrent programming concepts.
• 3+ years of Python programming skills.
• Knowledge of clean architecture and data modeling.

Responsibilities

• Developing advanced manufacturing software for optical transceiver testing.
• Writing drivers and managing laboratory equipment for testing.
• Integrating complex testing functionality into manufacturing software.
• Scale manufacturing software for thousands of units daily.

Skills

C#/.NET experience

Concurrent programming

Python programming

Data modeling with MongoDB

Analytical mindset

Git & CI/CD fluency

MongoDB

Remote debugging

Tools

GitHub Actions

PowerShell scripting

PowerShell

Bash

Job description

ABOUT LUMILENS

At Lumilens we are building the critical photonics infrastructure that powers tomorrow’s AI supercomputing. From chip-to-chip optical interconnects to scalable photonic engines, Lumilens is unlocking a new era of computing faster, cooler, and massively more efficient.

We’re a well-funded startup backed by Mayfield and led by veterans who’ve built and scaled some of the most transformative technologies in the industry. This isn’t incremental innovation, it’s a ground-floor opportunity to rethink the optical layer from the silicon up. You’ll work alongside a team of world-class engineers solving some of the hardest challenges in optics, systems, and scale. Every line of code, every design decision, every breakthrough you help deliver will shape the infrastructure of tomorrow.

If you're looking for mission, momentum, and the chance to make an outsized impact—jump on the rocket ship. We’re just getting started ... and we are building a Team in Kraków!

What You Will Work On

• C# / .NET desktop application — Advanced manufacturing software for optical transceiver testing. A GUI application built with MVVM architecture, featuring multi-threaded test execution, instrument resource management, and RPC services.
• Hardware integration — Writing drivers and control code for laboratory equipment, managing parallel test execution and handling complex locking across instruments.
• Python test scripts & libraries – Our manufacturing software draws the best from both worlds. You will have the opportunity to integrate complex testing functionality based on Python code embedded natively into the .NET application.
• Manufacturing scale - You will be developing software that runs on manufacturing lines, producing thousands of units daily.

Required Skills:

• 5+ years of C#/.NET — experience with GUI (WPF or similar framework), MVVM, async/await, thread safety, and class library design
• Strong command of concurrent programming — designing thread-safe systems, avoiding race conditions, and reasoning about execution across multiple threads and processes
• Experience with .NET 8 or later
• 3+ years of Python — OOP, pytest, abstraction-driven design
• Solid understanding of clean architecture — separation of concerns, dependency inversion, dependency injection, and testability
• MongoDB or similar document database — data modeling, querying, and managing test results at scale
• Analytical mindset — proven ability to break down complex multi-component failures, trace issues across process boundaries, and design reliable solutions under ambiguity
• Ability to debug remotely without direct debugger access — diagnosing issues via logs, traces, and telemetry

Infrastructure & Tooling

• Git & CI/CD fluency — GitHub Actions, artifact pipelines, versioning strategies, and automated deployment to remote Windows machines
• Bash and/or PowerShell scripting for automation, remote management, and deployment
• Systems-level thinking

Nice to Have

• Experience with test and measurement instruments (oscilloscopes, spectrum analyzers, power meters)
• Experience with Unit Tests: xUnit, MSTest, etc.
• Knowledge of optical communications, photonics, or transceiver technology
• Python.NET experience
• Familiarity with hardware interfaces – serial communication, TCP sockets, low-level protocols and interfaces (I2C, GPIB), and instrument communication standards (SCPI, VISA)
• Familiarity with factory/manufacturing software or MES integration

What we offer

• Competitive salary commensurate with experience
• Professional development opportunities and certification support
• Access to cutting-edge technology and cloud platforms
• Collaborative work environment with cross-functional teams

*Lumilens is an equal opportunity employer. All qualified applicants will receive consideration without regard to race, color, religion, gender, identity, orientation, veteran status, disability, or any other legally protected status.