Senior Software Engineer (.NET / Windows Services)

Position Overview The Senior Software Engineer (.NET / Windows Services) is a technical leader responsible for designing, developing, and supporting mission-critical Windows Services, backend processing applications, and enterprise integration solutions built on Microsoft technologies. This role focuses on building highly reliable, scalable, and performant long-running services that support core business operations, data processing, system integrations, and automation workflows. The Senior Engineer collaborates closely with Product, QA, Database, Infrastructure, and Delivery teams to deliver robust solutions, modernize legacy applications, improve system reliability, and establish engineering best practices across the software development lifecycle. Key Responsibilities Windows Services & Backend Application Development Design, develop, maintain, and support enterprise applications using C#, .NET Framework, .NET 6+, and Windows Services . Build and enhance long-running background processing services, scheduled jobs, batch processing systems, and automation solutions. Develop and maintain integrations with internal and third-party systems using APIs, file-based interfaces, messaging technologies, and database-driven workflows. Lead modernization initiatives by refactoring or migrating legacy and .NET Framework Windows Services to modern .NET platforms. Implement robust exception handling, retry mechanisms, fault tolerance, and service recovery capabilities. Apply engineering best practices including SOLID principles, dependency injection, asynchronous programming, and maintainable architectural patterns. Produce secure, testable, and high-performance solutions that support business-critical operations. Technical Leadership Lead complex development initiatives and provide technical ownership for critical Windows Service applications. Guide architecture decisions related to performance, scalability, maintainability, and operational reliability. Conduct comprehensive code reviews and mentor team members on development standards and best practices. Identify technical risks, performance bottlenecks, and operational concerns early in the development lifecycle. Drive application modernization and continuous improvement initiatives across legacy and current platforms. Cross-Functional Collaboration Collaborate with Business Analysts, Product Owners, and stakeholders to understand business requirements and translate them into technical solutions. Partner with QA teams to improve test automation, application stability, and release quality. Work closely with Infrastructure and DevOps teams to optimize deployments, service monitoring, and operational support processes. Support Production Support and Operations teams in troubleshooting, root cause analysis, and issue resolution. Participate in release planning, risk assessment, and production readiness reviews. Database & Integration Engineering Design, develop, and optimize SQL Server database solutions supporting enterprise-scale applications and processing services. Develop complex T-SQL stored procedures, functions, triggers, views, and ETL-related processes . Perform database performance tuning, index optimization, execution plan analysis, and query optimization. Design and implement integration solutions using: REST APIs SOAP services Message queues File transfers (CSV, XML, JSON) SFTP integrations Windows scheduled processes Collaborate with DBAs and architects on schema design, performance optimization, data governance, and security best practices. Performance, Monitoring & Supportability Monitor, troubleshoot, and optimize Windows Services running in production environments. Implement comprehensive logging, monitoring, alerting, and diagnostic capabilities. Analyze service performance, memory consumption, application health, and system resource utilization. Conduct root cause analysis and implement preventive measures for recurring production issues. Follow secure coding standards and ensure compliance with organizational security requirements. Mentorship & Continuous Improvement Mentor junior and intermediate engineers through coaching, code reviews, and technical guidance. Contribute to development standards, reusable components, and shared frameworks. Promote automation, operational excellence, and continuous improvement initiatives. Create and maintain technical documentation, support procedures, and operational runbooks. Foster knowledge sharing and technical excellence across the team. Skills & Qualifications Required 5+ years of professional experience developing enterprise applications using C#, .NET Framework, and/or .NET 6+ . Strong experience designing, developing, and supporting Windows Services, background processing applications, and scheduled jobs . Extensive knowledge of C#, multithreading, asynchronous programming, and object-oriented design principles . Experience maintaining and modernizing legacy and .NET Framework applications. Strong SQL Server expertise, including: Stored procedures Query optimization Database design Performance tuning Indexing strategies Experience implementing system integrations using APIs, file-based interfaces, messaging platforms, and database-driven workflows. Strong troubleshooting and production support experience within enterprise environments. Proficiency with Git, Azure DevOps, CI/CD pipelines, and release management processes. Experience working in Agile (Scrum/Kanban) development environments. Preferred Experience developing Windows Services using .NET Worker Services and Background Services . Experience with enterprise job scheduling and automation platforms. Knowledge of messaging technologies such as MSMQ, RabbitMQ, Azure Service Bus, or Kafka . Experience with monitoring and observability tools such as Splunk, ELK, App Insights, Grafana, or Datadog . Experience with cloud-hosted service workloads in Microsoft Azure. Experience with PowerShell scripting and deployment automation. Exposure to Docker and containerized background services. Bachelor's degree in Computer Science, Engineering, or related field, or equivalent practical experience. Nice-to-Have Domain Experience High-volume transaction processing systems. File processing and data migration platforms. Financial services, market data, insurance, or enterprise operations systems. 24/7 business-critical production support environments. We are looking for intellectually curious people, passionate about the bigger picture of how technology industry is evolving, ready to ask difficult questions and deal with complicated scenarios! If you are creative and a problem solver, this is the place to be as will be supporting you to fast-forward your career! We enhance each employee’s potential through personal development through a wide range of learning tools both formal and informal. LSEG 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 purpose is the foundation on which our culture is built. Our values of Integrity, Partnership, Excellence and Change 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. Working with us means that you will be part of a dynamic organisation of 25,000 people across 65 countries. However, we will value your individuality and enable you to bring your true self to work so you can help enrich our diverse workforce. You will be part of a collaborative and creative culture where we encourage new ideas and are committed to sustainability across our global business. You will experience the critical role we have in helping to re-engineer the financial ecosystem to support and drive sustainable economic growth. Together, we are aiming to achieve this growth by accelerating the just transition to net zero, enabling growth of the green economy and creating inclusive economic opportunity. LSEG offers a range of tailored benefits and support, including healthcare, retirement planning, paid volunteering days and wellbeing initiatives. We are proud to be an equal opportunities employer. This means that we do not discriminate on the basis of anyone’s race, religion, colour, national origin, gender, sexual orientation, gender identity, gender expression, age, marital status, veteran status, pregnancy or disability, or any other basis protected under applicable law. Conforming with applicable law, we can reasonably accommodate applicants' and employees' religious practices and beliefs, as well as mental health or physical disability needs. Career Stage: Senior Associate London Stock Exchange Group (LSEG) Information: Join us and be part of a team that values innovation, quality, and continuous improvement. If you're ready to take your career to the next level and make a significant impact, we'd love to hear from you. LSEG 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 purpose is the foundation on which our culture is built. Our values of Integrity, Partnership , Excellence and Change 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. Working with us means that you will be part of a dynamic organisation of 25,000 people across 65 countries. However, we will value your individuality and enable you to bring your true self to work so you can help enrich our diverse workforce. We are proud to be an equal opportunities employer. This means that we do not discriminate on the basis of anyone’s race, religion, colour, national origin, gender, sexual orientation, gender identity, gender expression, age, marital status, veteran status, pregnancy or disability, or any other basis protected under applicable law. Conforming with applicable law, we can reasonably accommodate applicants' and employees' religious practices and beliefs, as well as mental health or physical disability needs. You will be part of a collaborative and creative culture where we encourage new ideas. We are committed to sustainability across our global business and we are proud to partner with our customers to help them meet their sustainability objectives. Our charity, the LSEG Foundation provides charitable grants to community groups that help people access economic opportunities and build a secure future with financial independence. Colleagues can get involved through fundraising and volunteering. LSEG offers a range of tailored benefits and support, including healthcare, retirement planning, paid volunteering days and wellbeing initiatives. Please take a moment to read this privacy notice carefully, as it describes what personal information London Stock Exchange Group (LSEG) (we) may hold about you, what it’s used for, and how it’s obtained, your rights and how to contact us as a data subject . If you are submitting as a Recruitment Agency Partner, it is essential and your responsibility to ensure that candidates applying to LSEG are aware of this privacy notice.