Software Developer in Chelmsford

We\’re looking to engage an experienced Full Stack Developer to deliver a defined package of security and compliance-focused enhancements to our client\’s web platform. This is a short-term, well-scoped contract focused on strengthening authentication, auditing, and application security within an existing production system. The Role You will be responsible for implementing several targeted improvements to a live ASP.NET MVC application, including: * Adding multi-factor authentication (MFA) to user login * Implementing step-up verification for sensitive user actions to confirm user presence at the point of authorisation * Enhancing audit logging to capture user actions with timestamps * Reducing security vulnerabilities by updating legacy libraries and resolving AppCheck warnings * Producing clear technical documentation and handing over to the internal team Tech Stack * ASP.NET MVC (.NET Framework 4.8) * C# * JavaScript, HTML, CSS * REST APIs Required Experience * Strong background in authentication and authorisation patterns * Experience securing high-risk or regulated user actions (e.g. approvals, authorisations) * Comfortable working independently on well-defined enhancements * Ability to work within an existing codebase and platform constraints * Clear documentation and handover skills Desirable * Experience in regulated environments * Familiarity with step-up authentication or electronic signature workflows * Pragmatic approach to improving security without large-scale rewrites For more info, contact Ruben Davis at Synergy