Definely is looking for a Lead Full Stack Engineer (.Net/WPF) to guide the evolution of our LegalTech products. In this hands-on leadership role, you will set the technical direction, architect scalable systems, and ensure the delivery of high-quality, performant applications—from modern WPF-based desktop software to robust cloud services. You'll be critical in mentoring engineers, shaping architectural decisions, and embedding best practices, while remaining a meaningful contributor to the codebase.
What You'll Do
- Define and drive the technical vision, architecture, and roadmap for both desktop and backend services.
- Lead architectural design sessions, ensuring scalable, secure, and maintainable solutions.
- Champion engineering best practices, including early-stage quality planning (Shift Left), design patterns, automated testing, and CI/CD implementation.
- Evaluate and introduce emerging technologies, such as AI-assisted coding and cross-platform frameworks, to improve productivity and innovation.
- Lead the development of complex WPF applications following modern design patterns like MVVM, leveraging data binding, templating, and modular architecture.
- Oversee and contribute to the implementation of scalable backend services, APIs, and libraries using .NET Core and cloud platforms like AWS or Azure.
- Ensure high-quality and testable code through proactive practices like early test planning, TDD, code reviews, and automation.
- Enable rapid release cycles with strong DevOps practices, ensuring confidence in every deployment.
- Promote and apply principles such as SOLID, DRY, KISS, and Shift-Left quality to reduce defects early in the SDLC.
- Lead initiatives to embed testing into architecture and development, improving testability and enabling earlier defect detection.
- Use profiling and diagnostics tools to address performance, memory, and runtime optimizations.
- Refactor legacy systems to modern standards, boosting maintainability, coverage, and stability.
- Leverage tools like Autofac and clean architecture patterns to maintain loosely coupled and testable codebases.
- Act as a mentor and coach, helping engineers improve their technical depth, test-first mindset, and overall quality focus.
- Collaborate with Product Managers, Designers, and other Engineering Leads to align product and engineering goals.
- Help recruit, onboard, and develop top-tier engineers to grow a high-performance team.
- Advocate for and implement AI-assisted development tools like GitHub Copilot and Claude Code to boost engineering velocity and quality.
- Identify and implement opportunities to automate workflows, reduce technical debt, and drive continuous delivery excellence.
- Drive a culture of early feedback through improved observability and testing strategies.
What We're Looking For
- 8+ years of professional software development experience with .NET/C#.
- 3+ years in a technical leadership role.
- Proven track record architecting and delivering Windows desktop applications using WPF, including custom controls, UI animations, and advanced XAML.
- Strong backend expertise with .NET Core, RESTful API design, and scalable service architecture.
- Familiarity with Shift-Left testing approaches, embedding quality early in the SDLC.
- Deep understanding of object-oriented design, design patterns, and principles like SOLID and TDD.
- Proficient with Visual Studio and/or JetBrains Rider, and skilled in using ReSharper for code quality and refactoring.
- Familiarity with AI-assisted tools like GitHub Copilot and Claude Code.
- Skilled with relational databases such as PostgreSQL and CI/CD pipelines using modern DevOps toolchains.
- Demonstrated leadership and mentoring skills with the ability to influence architecture and cross-functional decisions.
- Pragmatic, strategic, and hands-on problem-solver who balances innovation with technical stability.
- Comfortable working in a fast-paced, agile environment.
Nice to Have
- Experience in product-focused or startup environments with rapid iteration cycles.
- Prior experience building VSTO Word Add-Ins.
- Familiarity with cross-platform frameworks like .NET MAUI, Blazor, or Avalonia.
- Knowledge of performance profiling, optimization, and enterprise-scale desktop deployment.
- Exposure to domain-driven design, microservices, or distributed systems.
Technical Stack
- .NET, C#, WPF, XAML, .NET Core
- AWS, Azure
- Autofac, PostgreSQL
- GitHub Copilot, Claude Code
- Visual Studio, JetBrains Rider, ReSharper
Benefits & Compensation
- Competitive Salary
- Impact & Growth in a fast-growing startup
- High-Performance Culture
- Prestigious Partnerships with top law firms and corporations
- Prime London Location & Hybrid Flexibility (office in Aldgate, hybrid 2-3 days/week)
- Ongoing Learning & Development
- 25 days of holiday per year plus UK bank holidays
- Competitive pension scheme
- Private Healthcare via Vitality, including dental and optical
- Flexible Working
- Enhanced Parental Leave
- Cycle to Work Scheme
- Workplace Nursery Scheme
- Top-Quality Equipment
Work Mode
This is a hybrid position based in London, UK, with an expectation to work from the Aldgate office 2-3 days per week.
Definely is a forward-thinking, collaborative team that prioritises innovation and people in a supportive, meritocratic environment.
