Salary: £132,000 - 143,000 per year Requirements: Experience delivering Outlook add-ins within enterprise environments Strong hands-on skills with Office.js, JavaScript or TypeScript, HTML, and CSS Deep understanding of Microsoft 365, Exchange Online, and behavioral differences between Outlook clients Experience integrating with Microsoft Graph, RESTful APIs, and modern authentication methods (OAuth / Azure AD) Exposure to CI/CD pipelines, Git-based version control, and automated testing practices (nice to have) Experience with Azure services such as App Services, Functions, Storage, or Key Vault (nice to have) Responsibilities: Architect, develop, and enhance Outlook add-ins using modern Microsoft frameworks and tools Ensure add-ins deliver a consistent experience across all Outlook clients, including desktop, browser, and mobile Connect add-ins to backend systems, APIs, and identity services such as Microsoft Graph and Azure Active Directory Collaborate closely with product owners, architects, QA, and operations Maintain compatibility across Exchange on-premises and Exchange Online deployments Produce and maintain technical documentation, design guidelines, and development standards Technologies: Active Directory Architect Azure Backend CI/CD CSS Git Support JavaScript Microsoft 365 Mobile OAuth TypeScript Office 365 Cloud DevOps macOS Web Windows More: We are seeking an experienced Senior Outlook Add-in Developer to join our team on a 10-month contract, paying between £500-£550 per day. This hybrid role is based in South Yorkshire, requiring 2-3 days in the office each week. You will support add-in solutions within enterprise-scale messaging environments, focusing on building robust, cross-platform Outlook add-ins that perform across various clients. We are committed to equal opportunities and welcome applications from diverse backgrounds. last updated 6 week of 2026