Senior Developer

We are seeking an experienced Outlook Add-in Developer to design, build, and support sophisticated Outlook add-ins within large-scale, hybrid enterprise messaging environments. The successful candidate will have proven experience delivering robust solutions that operate seamlessly across Windows, macOS, web, and mobile Outlook clients, and across both on-premises Exchange and Microsoft 365 Exchange Online.

This role operates within a highly regulated financial services environment and requires close collaboration with cross-functional teams in an Agile delivery model to ensure solutions meet high standards for security, scalability, reliability, and performance.

The role is INSIDE of IR35 and £550 P/D

• Design, develop, enhance, and support Outlook add-ins using Office.js and related Microsoft technologies
• Deliver consistent functionality across Outlook for Windows, macOS, Web, and Mobile
• Integrate Outlook add-ins with backend services, APIs, and identity platforms such as Microsoft Graph and Azure Active Directory
• Ensure full compatibility with both Exchange on-premises and Exchange Online (Microsoft 365)
• Optimise solution performance, resilience, and security in high-volume email environments
• Collaborate closely with product owners, solution architects, QA, and operations teams within an Agile/Scrum framework
• Actively participate in sprint planning, backlog refinement, code reviews, and retrospectives
• Troubleshoot, diagnose, and resolve issues across multiple Outlook clients and platforms
• Contribute to technical documentation, solution designs, coding standards, and best practices

• Demonstrated experience developing Outlook add-ins within enterprise environments
• Hands-on experience supporting hybrid Exchange environments (on-premises and Exchange Online)
• Solid understanding of Microsoft 365
  , Exchange Online, Outlook desktop clients, and Outlook Web App behaviour and limitations
• Experience delivering solutions across Windows, macOS, Web, and Mobile Outlook clients
• Familiarity with Microsoft Graph
  , RESTful APIs, and authentication using OAuth / Azure AD
• Experience implementing telemetry, logging, and monitoring for Outlook add-ins
• Understanding of deployment, governance, and administrative considerations for Outlook add-ins within Microsoft 365
• Proven experience working in Agile delivery environments (Scrum or Kanban)
• Strong collaboration skills, with the ability to work effectively across distributed and cross-functional teams
• Ability to translate complex business and regulatory requirements into scalable, maintainable technical solutions

• Experience with Azure services
  , including App Services, Functions, Storage, and Key Vault
• Knowledge of email security, compliance, and data governance
  , particularly within regulated enterprise or financial services environments
• Experience with CI/CD pipelines
  , version control systems (e.g. Git), and automated testing frameworks