Transforming Office Productivity
Through Custom Add-ins
Professional Microsoft Office and Google Workspace development services tailored to automate workflows and boost business efficiency.




















Who We Are
MSOfficeAddin.com is a specialized development agency focused on custom Microsoft Office and Google Workspace add-ins. Over the past five years we have shipped 250+ projects for clients worldwide, including businesses in Germany and across Europe.
250+
Projects Delivered
98%
Satisfaction Rate
5+
Years Experience
30+
Countries Served
Why Choose Us
- Office.js Specialists, 250+ add-ins delivered since 2021
- Delivery in 2–8 weeks (standard) or 6–12 weeks (Graph-integrated)
- Azure AD SSO, MSAL OBO flow, Microsoft Graph security on every project
- Registered AppSource Publisher, avg. 3–7 day certification turnaround
- 50+ VSTO-to-Office.js migrations completed for enterprise clients
Companies that trust our add-ins




















What We Do

Microsoft Office Add-ins Development
MSOfficeAddin builds custom Microsoft Office add-ins for Excel, Outlook, Word, PowerPoint, SharePoint, and Teams using Office.js and the Microsoft 365 platform. From CRM-integrated Outlook add-in workflows to financial-automation Excel tools, our certified developers deliver AppSource-ready, cross-platform solutions for enterprise teams across the US, UK, and Australia.
Specialized Solutions

Office Add-in Integration Services
Connect your Office add-ins to SAP, Salesforce, Power BI, AI models, REST APIs, and enterprise systems. We build the integration layer so your data flows where your team already works.
Specialized Solutions

Authentication & Identity
We build the authentication layer for Office add-ins, including Microsoft SSO, OAuth 2.0, Azure AD app registration, and multi-tenant identity. Your users sign in once and the add-in handles everything else.
Specialized Solutions

AppSource Publishing Services
We provide end-to-end Microsoft AppSource submission and certification support, from manifest preparation through reviewer communication and resubmission. We publish your Office add-in to the Microsoft marketplace so enterprise IT admins can deploy it across their organization.
Google Workspace Add-ons
Custom Google Workspace add-on development for Sheets, Docs, Gmail, and Drive. Professional Apps Script and REST API solutions for Google Workspace automation.
Specialized Solutions
Our Delivery Process
A structured approach to turning requirements into enterprise solutions.
Discovery
Scoping call + workflow analysis. We document Office.js API requirements and define the manifest, permissions, and authentication model before writing a line of code.
Design
Fluent UI wireframes and task-pane architecture. We align on API requirement sets (e.g., ExcelApi 1.14, Mailbox 1.10) to ensure cross-version compatibility.
Build
Agile sprints using Office.js, React, TypeScript, and Azure. Daily builds are testable via sideloading in your own Microsoft 365 tenant.
Deploy
Security audit, manifest validation, and AppSource submission. Microsoft review typically completes in 3–7 business days.
Support
Post-launch monitoring and compatibility updates for new Microsoft 365 releases. Response time: 24 business hours.
What Our Clients Say
Join 100+ businesses who trust us with their critical Office automation and enterprise add-in development.