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Join to apply for the Lead Full Stack Engineer (.Net/WPF) role at Definely

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The role

We’re seeking a seasoned .NET Technical Lead with deep expertise in .NET/C# and WPF to guide the evolution of our LegalTech products. This is a hands-on leadership and technical role where you’ll set technical direction, architect scalable systems, and ensure the delivery of high-quality, performant applications—ranging from modern WPF-based desktop software to robust cloud services.

You’ll play a critical part in mentoring engineers, shaping architectural decisions, and embedding best practices, while still contributing meaningfully to the codebase.

This is a unique opportunity to lead from the front at a fast-growing company whose products are trusted by some of the world’s leading law firms and legal teams.



Key responsibilities

Technical Leadership & Strategy

• 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 (e.g., AI-assisted coding, cross-platform frameworks) to improve productivity and product innovation.
  
  

• Lead the development of complex WPF-based applications following modern design patterns such as 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 such as 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 ensure product and engineering goals remain aligned.
• Help recruit, onboard, and develop top-tier engineers, growing a high-performance team.
  
  

• Advocate for and implement AI-assisted development tools (e.g., GitHub Copilot, 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, enabling faster and more reliable development through improved observability and testing strategies.
  
  

• 8+ years of professional software development experience with .NET/C#, including 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.
• Familiar with Shift-Left testing approaches, embedding quality early in the SDLC and enabling team-wide accountability for code correctness.
• 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 (e.g., 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.
  
  

• 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.
  
  

• We offer a highly competitive salary that reflects your skills, experience, and contributions.
  
  

• Join a fast-growing startup where your ideas matter; experiment, innovate, and see your work come to life.
  
  

• Work in a truly meritocratic environment alongside ambitious, driven professionals who push each other to excel.
  
  

• Collaborate with some of the world’s top law firms, financial institutions, and multinational corporations.
  
  

• Enjoy a vibrant office in the heart of Aldgate with the option to work in a hybrid environment. We tend to come into the office 2-3 times a week, although you can come in more!
  
  

• Access top-tier training, mentorship, and continuous support to advance your career.
  
  

• Enjoy 25 days of holiday per year, plus UK bank holidays, to recharge and unwind.
  
  

• Secure your future with our competitive pension scheme.
  
  

• Access to Vitality healthcare, including dental and optical.
  
  

• Work in a way that suits your lifestyle, with the freedom to balance professional and personal priorities.
  
  

• We support working parents with generous parental leave policies that go far beyond statutory requirements.
  
  

• Save on a new bike and accessories while promoting a healthier, more sustainable commute.
  
  

• Saving working parents lots of money through our salary sacrifice scheme!
  
  

• Get the tools you need to perform at your best, from cutting-edge tech to ergonomic office setups.
  
  

Seniority level

• Seniority level

  Mid-Senior level

Employment type

• Employment type

  Full-time

Job function

• Job function

  Engineering and Information Technology

• Industries

  Software Development

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