Senior Software Engineer (.NET)

Key Responsibilities Modern Application Architecture & Development Architect, develop, and maintain applications using .NET 6+, C#, ASP.NET Core, and modern frameworks. Build and enhance RESTful APIs, microservices, messaging components, and background workers. Lead modernization efforts by refactoring or migrating legacy VB.NET and older .NET Framework applications to modern .NET. Apply engineering best practices including SOLID principles, domain‑driven design (DDD), dependency injection, asynchronous programming, and clean architecture patterns. Write secure, testable, performant code and drive engineering excellence across the team. Technical Leadership Lead complex development initiatives with autonomy and technical ownership. Guide the team on system architecture, code quality, performance optimization, and maintainability. Conduct in‑depth code reviews and mentor developers to elevate technical capabilities. Anticipate technical risks and provide mitigation strategies during planning and design phases. Cross‑Functional Collaboration Partner with Product Managers to clarify requirements, roadmap impacts, and technical feasibility. Collaborate with QA to enhance automated testing, shift‑left quality practices, and overall reliability. Work with Dev Ops to optimize CI/CD pipelines, deployment workflows, infrastructure-as-code, and cloud readiness. Support Delivery Management by identifying risks, dependencies, and technical constraints early. Database & Integration Engineering Design, implement, and optimize relational database structures using SQL Server, with a strong focus on stored procedures, views, indexing strategies, and query performance. Develop high‑performance T‑SQL code, including complex stored procedures, functions, triggers, and optimized queries for large datasets. Perform database performance tuning, index analysis, query plan evaluation, and workload optimization to ensure scalability and reliability. Integrate applications with internal and external systems using REST APIs, event streams, message queues, file‑based exchanges, or service bus technologies. Collaborate with DBAs and architects on capacity planning, schema design, data governance, and best practices for secure data access. Performance, Observability & Security Perform performance profiling, memory optimization, and load testing. Implement secure coding practices aligned with OWASP guidance and least‑privilege standards. Build resilient, observable systems with structured logging (Serilog/ELK), metrics, distributed tracing, and robust error handling. Mentorship & Continuous Improvement Mentor junior and intermediate developers through pairing, coaching, and knowledge-sharing. Influence and contribute to internal frameworks, shared libraries, and engineering standards. Advocate for continuous improvement in development flow, automation, tooling, and Dev Ops maturity. Help foster a learning culture through documentation, workshops, and code craftsmanship. Skills & Qualifications Required 5+ years of professional experience developing applications with the modern .NET ecosystem. Strong expertise in C# and hands‑on experience with modern .NET (6+), ASP.NET Core, Web API, LINQ, and object-oriented design. Experience maintaining or migrating legacy VB.NET or .NET Framework applications. Hands-on experience building and consuming REST APIs and working in microservices, modular, or distributed architectures. Strong SQL Server knowledge, including data modeling, query optimization, and performance tuning. Proficiency with Git, CI/CD pipelines (Azure Dev Ops/Git Hub Actions), and automated deployment workflows. Experience working in Agile (Scrum/Kanban) environments. Preferred Experience with cloud platforms, ideally Microsoft Azure (App Services, Azure Functions, Key Vault, Storage, Service Bus, etc.). Experience with Docker, containers, and Kubernetes/AKS. Knowledge of DDD, event-driven architecture, messaging patterns (e.g., Service Bus, Kafka). Exposure to front-end frameworks (React, Angular, Blazor) is an asset. Bachelor’s degree in Computer Science, Engineering, or related field—or equivalent practical experience. 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. If you want to apply for a job, please click the Apply button. You will then be redirected to our Careers sign-in page where you can enter your existing credentials or set up an account with us. If there is nothing that currently suits you, feel free to send us your Resume/CV 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. Our Data & Analytics, Capital Markets and Post Trade divisions have a combined power that provides a comprehensive, integrated suite of trusted financial market infrastructure services to help our customers pursue their ambitions. Explore our divisions LSEG is headquartered in the United Kingdom, with significant operations in 70 countries across Europe, the Middle East, Africa, North America, Latin America and Asia Pacific. Find out more Get to know some of our people who are pushing the boundaries of technology, finance and more around the world.