Office add-in development services
Task panes and ribbon commands across Outlook, Word, Excel, and PowerPoint using Office.js — one codebase, all hosts.
Microsoft 365
Microsoft 365 Developer
Microsoft 365 development creates add-ins and integrations for supported Outlook, Word, Excel, and PowerPoint clients using Office.js, Microsoft Graph, and Entra ID. It is intended for organizations that need to place business workflows inside Microsoft 365 or connect Microsoft data to another system, with compatibility determined by each host and requirement set.
What I build
What is included in Microsoft 365 development?
Microsoft Graph integration
Reading and automating mail, calendar, files, users, and Teams through the Microsoft Graph API with delegated or application permissions.
SSO & Entra ID
Single sign-on with MSAL and Entra ID (Azure AD), least-privilege scopes, and admin-consent flows ready for enterprise rollout.
AppSource & deployment
Manifest authoring, Microsoft's validation, and publishing to AppSource or centralized deployment through the 365 admin center.
Problems this solves
What problems can Microsoft 365 development solve?
- Business logic that lives outside Office, so staff constantly switch apps and re-key data.
- An add-in that has to work identically on Outlook/Excel desktop, web, and Mac.
- Enterprise SSO and admin-consent requirements that block a naive add-in from shipping.
- AppSource submissions bouncing on validation because the manifest or permissions are wrong.
Example use cases
What does Microsoft 365 development look like in practice?
CRM context in Outlook
An Outlook add-in that shows the sender's deal and ticket history on the open email, pulled live via Microsoft Graph.
Live figures in Excel
An Excel add-in with custom functions streaming live data from an internal API straight into cells.
Org-wide rollout
Deployed an add-in to an entire tenant through the admin center with Entra ID SSO and no per-user install.
Tech stack
What technologies power Microsoft 365 development?
Add-ins
- Office.js
- React
- TypeScript
Platform
- Microsoft Graph
- MSAL
- Entra ID SSO
Hosting
- Azure Static Web Apps
- Azure Functions
Delivery
- Unified manifest
- AppSource
- Centralized deployment
Explore microsoft 365
What does Microsoft 365 development cover?
Microsoft 365 is broad. Here are the specific add-in services under it — go deeper on the host you need:
office plugin development
Office add-in development creates web-based task panes, ribbon commands, and document or workbook tools for supported Word, Excel, Outlook, and PowerPoint clients. It is intended for organizations replacing manual Office workflows or assessing whether a legacy VSTO or COM plugin can move to Office.js, subject to the APIs available in each host.
outlook plugin development
Outlook add-in development creates tools that operate in supported reading, compose, and event-based Outlook contexts using Office.js and, where required, Microsoft Graph. It is intended for organizations that need email or calendar workflows, CRM context, validation, or internal actions available from Outlook, with features limited by the client and Mailbox requirement set.
excel add in developer
Excel add-in development creates custom functions, task panes, worksheet automation, and API-connected data workflows using Office.js. It is intended for organizations that need calculations, reporting, imports, or two-way data synchronization inside supported Excel clients, with availability determined by platform and requirement set.
document automation software
Document automation uses templates, structured data, add-ins, and workflow integrations to generate or process documents with less manual assembly. It is intended for teams that create recurring contracts, proposals, reports, or approval packages in Word or server-side systems.
Process
How does Microsoft 365 development work?
01
Scope the workflow
Clarify Office apps, Graph data, permissions, and deployment target.
02
Build the add-in
Office.js + React task panes and a secure Graph backend.
03
Secure & validate
SSO, scopes, and manifest hardening against Microsoft's rules.
04
Deploy & support
AppSource or tenant deployment, with docs and handoff.
Related services
Office Plugin Development
Office add-in development creates web-based task panes, ribbon commands, and document or workbook tools for supported Word, Excel, Outlook, and PowerPoint clients. It is intended for organizations replacing manual Office workflows or assessing whether a legacy VSTO or COM plugin can move to Office.js, subject to the APIs available in each host.
Outlook Plugin Development
Outlook add-in development creates tools that operate in supported reading, compose, and event-based Outlook contexts using Office.js and, where required, Microsoft Graph. It is intended for organizations that need email or calendar workflows, CRM context, validation, or internal actions available from Outlook, with features limited by the client and Mailbox requirement set.
Google Apps Script Developer
Google Apps Script development creates automations and add-ons for Google Sheets, Docs, Gmail, Drive, Forms, and Calendar. It is intended for Google Workspace teams that need triggers, custom menus or sidebars, document workflows, external API connections, or private and Marketplace add-on deployment.
FAQ
Questions, answered
- What's the difference between an Office add-in and an old VSTO plugin?
- VSTO/COM plugins are Windows-only and install per machine. Office.js add-ins can target supported Outlook, Word, Excel, and PowerPoint clients on Windows, Mac, and the web, with capability checks for host and version differences.
- Do add-ins work on desktop, web, and Mac?
- Yes. A single Office.js add-in runs across Office on Windows, Mac, iPad, and the web, with capability checks where a host differs.
- Can you integrate Microsoft Graph for mail, calendar, and files?
- Yes — Microsoft Graph integration is central to my work, covering mail, calendar, files, users, and Teams with delegated or application permissions.
- Do you set up SSO with Entra ID?
- Yes. I implement single sign-on with MSAL and Entra ID (Azure AD) using least-privilege scopes suitable for enterprise environments.
- Can you publish to AppSource or deploy internally?
- Both. I prepare the manifest, pass Microsoft's validation, and either publish to AppSource or deploy privately via centralized deployment in your admin center.
Let's build it together
Email me with what you need — I'll reply with a clear plan and next steps. Prefer chat? WhatsApp works too.