Lead Software Engineer (C#)

London Stock Exchange Group; Gdynia; On-site; PLN 120,000 - 150,000; Full time

Job summary

A global financial markets infrastructure provider in Gdynia is seeking a seasoned engineer to design and optimize high-performance .NET applications, focusing on multithreading and Azure services. You will support junior developers and shape technical decisions, with a strong emphasis on product-focused thinking and team collaboration. A solid background in SQL Server and Azure is essential for success in this role.

Qualifications

• 5+ years of professional engineering experience with a track record of delivering production systems.
• Strong expertise in .NET with deep experience in multithreading and async patterns.
• Solid SQL Server skills, including query optimization and stored procedures.

Responsibilities

• Design, build, and optimize high-performance .NET applications.
• Support and mentor junior developers, providing technical guidance.
• Work with SQL Server to create efficient, scalable database solutions.

Skills

.NET

multithreading

asynchronous programming

SQL Server

Azure

Angular

Tools

Terraform

CI/CD pipelines

Job description

* Design, build, and optimize high-performance .NET applications with a heavy focus on **multithreading** and **asynchronous programming**.* Build and maintain services and infrastructure in **Azure**.* Support and mentor junior developers, offering technical guidance and code review.* Take initiative on technical improvements, troubleshooting, and system reliability.**What You’ll Bring:**Must-Have Skills* Strong expertise in **.NET** with deep experience in **multithreading** and **async patterns -** you understand concurrency, race conditions, locking, and performance tuning.* Solid **SQL Server** skills, including query optimization, indexing strategies, and stored procedures.* Hands-on **Azure** experience - App Services, Functions, Service Bus, storage, or related cloud components.* 5+ years of professional engineering experience with a track record of delivering production systems.Nice-to-Have Skills* Basic **Angular** knowledge for full-stack collaboration and UI integration.LSEG (London Stock Exchange Group) is more than a diversified global financial markets infrastructure and data business. We are dedicated, open-access partners with a dedication to excellence in delivering the services our customers expect from us. With extensive experience, deep knowledge and worldwide presence across financial markets, we enable businesses and economies around the world to fund innovation, manage risk and create jobs. It’s how we’ve contributed to supporting the financial stability and growth of communities and economies globally for more than 300 years. Through a comprehensive suite of trusted financial market infrastructure services – and our open-access model – we provide the flexibility, stability and trust that enable our customers to pursue their ambitions with confidence and clarity!LSEG is headquartered in the United Kingdom, with significant operations in 70 countries across EMEA, North America, Latin America and Asia Pacific. We employ 25,000 people globally, more than half located in Asia Pacific.**Role Summary:**We’re looking for a seasoned engineer who thrives on ownership, delivers with consistency, and thinks like a product builder-not just a coder. You’ll play a key role in shaping technical decisions, supporting less-experienced teammates, and freeing the lead engineer from low-level implementation details through reliable execution.**What You’ll Be Doing:** Work with **SQL Server** to create efficient, scalable database solutions. Collaborate closely with the product team and think deeply about end-user experience and business impact. * **CI/CD pipelines** (Azure DevOps, GitHub Actions, etc.) for smooth delivery and deployment automation.* **Terraform** or similar IaC tools for provisioning and managing cloud environments.Soft Skills We Value* Ownership attitude - someone who picks up problems and sees them through.* Proactiveness and initiative - you anticipate needs rather than waiting for instructions.* Product-focused thinking - your work reflects the end user’s reality.* Dependability - a great teammate who others can trust and who helps maintain a healthy, collaborative engineering environment.underpin our purpose and set the standard for everything we do, every day. They go to the heart of who we are and guide our decision making and everyday actions.Our purpose is the foundation on which our culture is built. Our values of **Integrity, Partnership**, **Excellence** and **Change** LSEG (London Stock Exchange Group) is a leading global financial markets infrastructure and data provider. Our purpose is driving financial stability, empowering economies and enabling customers to create sustainable growth. Our culture of connecting, creating opportunity and delivering excellence shapes how we think, how we do things and how we help our people fulfil their potential.