Add-In Developer (Office.js) | Hybrid | London / Sheffield | 10 Month Contract | £500 - £550 inside IR35 | Outlook Add Ins
About the Role
We're looking for a seasoned Senior Outlook Add-in Developer to join our team and take ownership of designing, building, and supporting sophisticated Outlook add-ins used in large, enterprise-scale environments.
This role is ideal for someone who thrives in complex messaging ecosystems and has hands-on experience delivering solutions that work flawlessly across Windows, macOS, web, and mobile Outlook clients, including hybrid Exchange setups spanning on-premises and Microsoft 365.
What You'll Be Doing
Architect, develop, and support Outlook add-ins using Office.js and modern web technologies
Ensure add-ins perform consistently across Outlook for Windows, Mac, Web, and Mobile
Integrate Outlook add-ins with backend services, APIs, and identity platforms such as Microsoft Graph and Azure
Focus on performance, security, and reliability in high-volume email scenarios
Diagnose and resolve issues across multiple Outlook clients and platforms
Core Technical Experience
Demonstrated experience building Outlook add-ins in enterprise environments
Strong skills in Office.js, JavaScript/TypeScript, HTML, and CSS
Hands-on experience with hybrid Exchange (on-prem + Exchange Online)
Solid understanding of Microsoft 365, Outlook desktop clients, and Outlook Web App behavior
Nice to Have
Experience with Azure services (App Services, Functions, Storage, Key Vault)
If this sounds like you, APPLY NOW!
Add-In Developer (Office.js) | Hybrid | London / Sheffield | 10 Month Contract | £500 - £550 inside IR35 | Outlook Add Ins
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