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