Tech Lead / Senior Software Engineer / Software Architect

Tech Lead / Senior Software Engineer / Software Architect .NET | C# | Python | AI | Architecture | London (Hybrid) Permanent: £80,000 - £110,000 + Benefits OR Contract: £600 - £700 per day Location: London City (1-2 days per week) Overview We're working with a well-known global organisation embarking on a major transformation of one of its core business-critical platforms. This is an opportunity to play a leading role in modernising a legacy product, improving its architecture, integrating it with wider enterprise systems, and introducing AI capabilities into both the product itself and the software development lifecycle. Rather than a large-scale rewrite, the platform will be modernised incrementally, requiring someone who can balance strategic architectural thinking with hands-on engineering delivery. You'll help shape the future technical direction while remaining close to the code. This role would suit an experienced Tech Lead, Senior Software Engineer or Software Architect who enjoys solving complex technical problems and building modern, scalable software. Role & Responsibilities • Lead the technical design and evolution of a large-scale business-critical platform. • Improve the existing architecture and define a pragmatic roadmap towards a modern, scalable solution. • Design and build new features using .NET, C# and Python. • Introduce AI-powered capabilities into the product to improve functionality and user experience. • Drive the adoption of AI-assisted software development tools and engineering best practices. • Design integrations with enterprise platforms, APIs and wider business systems. • Work closely with Product, Architecture and Engineering teams to deliver incremental improvements. • Mentor developers and provide technical leadership across the engineering function. • Champion software quality, automation, testing and modern engineering standards. Skills & Experience • Strong commercial experience with .NET, C# or Python development experience. • Previous experience as a Tech Lead, Lead Developer, Senior Software Engineer or Software Architect. • Strong software architecture and solution design experience, including modernisation of legacy applications. • Experience designing scalable, maintainable and highly available systems. • Knowledge of API design, system integration and enterprise application architecture. • Experience delivering software through Agile environments. • Exposure to AI technologies, LLMs or AI-enabled products would be highly desirable. • Experience using AI developer tools such as GitHub Copilot, Claude Code, Codex or similar would be an advantage. • Excellent communication skills with the ability to work across technical and business stakeholders. This is an excellent opportunity to join a high-profile transformation programme where you'll have genuine influence over the technical direction of a flagship platform while helping shape how AI is embedded into both the product and the engineering team.