Sr. Full Stack Developer (JS Web Framework/Svelte + C# .NET)

Responsible for the modernization and continued development of enterprise application frontends built on the legacy .NET platform and Java J2EE/Swing. This role involves frontend UI development using Svelte or other modern JavaScript/TypeScript frameworks and some backend development using C#/ASP.NET Core and Java. You will lead the refactoring of legacy systems into modular, API-driven architectures and transition desktop-based WinForms UIs to responsive, maintainable, modern web interfaces. This position requires experience with Microsoft technologies, modern front-end frameworks, and development in a regulated (e.g., cGMP) environment.

Position works remote from home office. Must be able to work UK hours (GMT & BST time zones).

ESSENTIAL DUTIES AND RESPONSIBILITIES:

Lead the migration of legacy .NET applications (Web Forms, WCF, etc.) and J2EE application frontends to modern JS Web Frameworks

Drive the transformation of UIs from WinForms, Java Swingf, or older technologies to Svelte or other JS web framework.

Help to build and maintain backend services using C#, Entity Framework, Java, and PostgreSQL or SQL Server.

Refactor monoliths into modular APIs and microservices.

Write and maintain unit, integration, and end-to-end tests.

Contribute to DevOps pipelines and CI/CD processes.

Collaborate with QA, Security, and Regulatory teams to maintain compliance with FDA 21 CFR Part 11, GAMP5, and cGMP standards.

Participate in Agile development practices and sprint ceremonies.

Document code and processes thoroughly.

Mentor junior developers.

Education & Experience:

• Bachelor s degree in Computer Science, Software Engineering, or related field.
• 5+ years of experience in full-stack development with:
  • JavaScript/TypeScript Web Frameworks - Svelte strongly preferred
  • CSS expertise
  • C# / ASP.NET Core / .NET 6+ / Java J2EE
  • SQL databases (PostgreSQL or SQL Server)
  • REST API design and implementation

Technical Skills:

• Object-oriented programming (OOP) and design patterns
• Modern JavaScript/TypeScript web frameworks (Svelte preferred)
• Test automation frameworks (xUnit, Playwright, or Cypress)
• Git, Azure DevOps, or equivalent ALM tools

Preferred Experience

• GxP or regulated software environment
• Laboratory systems (LIMS, automation tools)
• Docker, OpenShift, or Kubernetes environments