Sr. Fullstack Engineer

Job Summary:

We are seeking a Senior Full Stack Engineer to own a product area end to end - design it, build it, and run it in production. You will set the engineering standard for a squad of four to six engineers, lead the modernisation of existing ASP.NET MVC systems into modular ASP.NET Core services, and act as the technical counterpart to product owners and client stakeholders.

This role is deliberately hands-on. You are expected to write and review code, make architecture decisions you can defend on cost and risk, and set how the team works with AI coding assistants and LLM-based features so that quality, security and IP are never traded for speed.

Key Responsibilities:

· Own one or more services end to end - architecture, implementation, deployment, monitoring and production support.

· Design .NET Core service architecture - API contracts and versioning, domain and service boundaries, async messaging, caching, and resilience patterns (retry, circuit breaker, idempotency).

· Lead the modernisation of legacy ASP.NET MVC applications into modular ASP.NET Core services using a strangler-fig approach, with a migration sequence the business can absorb.

· Own the SQL Server data layer at scale - data modelling, indexing strategy, partitioning, safe production migrations, and the call on when to cache, denormalise or offload.

· Set the frontend standard in Angular or React - application and component architecture, a typed API client layer generated from the API contract, predictable state management (signals and RxJS, or hooks and a store), code splitting and lazy loading, enforced performance budgets, and an accessible reusable component library.

· Design and integrate AI / LLM capabilities into enterprise applications - retrieval and grounding, structured outputs, token and cost budgeting, latency and fallback behaviour, PII boundaries, and evaluation before release.

· Define how the team uses AI coding assistants - repository-level instructions, review standards for AI-generated code, and guardrails that protect quality, security and client IP.

· Own the non-functional requirements - security (OAuth 2.0 / OIDC, Microsoft Entra ID, RBAC, secrets and certificate management), observability, performance and cloud cost.

· Run and improve CI/CD - build, test and security gates, environment promotion, slot or blue-green releases, and a rollback path that has actually been tested.

· Lead incident response for owned services - triage, mitigation, root-cause analysis, a written post-mortem and follow-through on the actions.

· Mentor three to five engineers - design reviews, pairing, code review, and raising the throughput of the team rather than only your own.

· Work directly with product owners and client stakeholders - scope, estimate, sequence, and push back with evidence when a plan does not hold.

· Contribute to solution design and pre-sales - effort estimates, architecture views and technical responses for new opportunities.

Mandatory Requirements:

· 8+ years of professional software engineering experience, including at least three in a senior, lead or architect capacity.

· Deep .NET Core / ASP.NET Core expertise - advanced C# (async and concurrency, memory and performance profiling), dependency injection, middleware, minimal APIs and MVC controllers.

· Proven REST API design at enterprise scale - versioning, contracts, idempotency, pagination, rate limiting and backward compatibility.

· Strong SQL Server - data modelling, indexing strategy, execution-plan analysis, stored-procedure tuning and zero-downtime migrations.

· Entity Framework Core in depth, including where to drop to raw SQL or Dapper and why.

· Advanced TypeScript, with architectural-level experience in Angular 16+ or React 18+ - application and module structure, state management (RxJS and signals, or hooks, context and a state library), rendering and re-render behaviour, and build and bundle optimisation.

· Hands-on Azure - App Service or Container Apps, Functions, Azure SQL, Service Bus, Key Vault, Entra ID and Application Insights.

· Ownership of CI/CD pipelines in Azure DevOps or GitHub Actions, including automated testing and security scanning.

· Application security - OWASP Top 10, authentication and authorisation design, secrets handling and data protection.

· Demonstrated production ownership - you have carried a system you designed through real incidents and change.

· A track record of mentoring engineers and running design and code reviews.

· Confident client-facing communication - able to present a design and its trade-offs to a non-technical stakeholder.

Good-to-Have Skills:

· Working knowledge of both Angular and React - our client estate uses both, and you may be asked to set the standard in either.

· Micro-frontends or module federation, and server-side rendering (Angular Universal or Next.js) where it earns its place.

· Microservices and event-driven architecture - Service Bus, Kafka, outbox pattern, eventual consistency.

· Kubernetes / AKS or Azure Container Apps in production.

· Infrastructure as Code - Bicep or Terraform.

· Python for data processing, automation or AI services.

· Hands-on LLM engineering - RAG pipelines, vector stores, tool calling and agentic patterns, MCP servers, and evaluation harnesses.

· Multi-tenant SaaS design, including data residency and sovereignty constraints.

· Regulated-domain exposure (BFSI, legal, healthcare) and the audit, traceability and compliance expectations that come with it.

· Experience in a consulting or client-facing delivery model