Microsoft 365 APIConnect Microsoft 365 without building on its API
Microsoft 365 has a REST API. Self-serve for any developer who registers an app in Microsoft Entra ID, but tenant data needs user consent or admin consent. If you're reading the docs because you need Microsoft 365 to talk to the rest of your stack, Caddi does that without you writing or maintaining integration code: you show it the job once, and it runs it across Microsoft 365 and your other tools.
- APIREST (JSON)
- AuthOAuth 2.0
- AccessSelf-serve
What the Microsoft 365 API gives you
- Type
- REST (JSON)
- Authentication
- OAuth 2.0 via Microsoft identity platform (Microsoft Entra ID), delegated or application permissions
- Who can get access
- Self-serve for any developer who registers an app in Microsoft Entra ID, but tenant data needs user consent or admin consent.
- What it covers
- Microsoft 365 data including users, groups, Outlook mail/calendar/contacts, OneDrive, SharePoint, Teams, Planner, OneNote, To Do, plus Entra ID and Intune.
- Limits
- No single global limit: throttling thresholds vary by service and scenario (see the service-specific limits page) and return 429 with Retry-After.
- Worth knowing
- Microsoft points large-volume data extraction to Microsoft Graph Data Connect instead of the Graph REST APIs.
Official docs: learn.microsoft.com. Checked September 2026. Vendors change access terms, so confirm with Microsoft 365 before you build.
Building on the Microsoft 365 API vs. having Caddi run it
| The job | Build it on the API | With Caddi |
|---|---|---|
| Getting access | Register an app, get Microsoft 365 credentials, and manage tokens and refreshes. | Connect your Microsoft 365 account once. Caddi holds the connection. |
| Writing the integration | A developer maps fields, handles pagination, retries and rate limits, and writes the sync. | You show Caddi the Microsoft 365 task the way you'd train a new hire. It writes verified code for it. |
| Steps the API doesn't cover | Screens with no endpoint stay manual, or need a separate RPA tool. | Caddi uses a secure, audited browser session where there's no API, in the same automation. |
| The other systems in the loop | Each extra tool is another API, another set of credentials, another integration to own. | One automation runs across all the tools the job touches. |
| Keeping it running | Someone owns the code when the API version, fields or your process change. | Every automation is reviewed before it runs in production, and every run is logged. |
Building on the API is the right call when you have engineers and the integration is your product. When the goal is getting Microsoft 365 work off someone's desk, the build is the slow part.
What teams usually want the Microsoft 365 API for
New Hire Tracker Cleanup
Caddi manages new hire onboarding follow-ups in an Excel tracker by categorizing employees, updating tracking fields, and removing duplicate entries.
Excel Transaction Sync
Caddi transfers new deal transaction data between Excel worksheets by creating a row for each transaction and mapping source values into the destination sheet.
Onboarding Tracker Cleanup
Caddi manages onboarding follow-ups from an onboarding report by classifying employees, updating tracker fields, and removing duplicate entries.
Outlook → Word → DMS
Caddi reads inbound requests in Outlook, drafts the response document in Word with current data, and files the finalized version in your DMS.
Microsoft 365 API questions
Does Microsoft 365 have an API?
Yes. Microsoft 365 has a REST API, authenticated with OAuth 2.0 via Microsoft identity platform (Microsoft Entra ID), delegated or application permissions. The official documentation is at https://learn.microsoft.com/en-us/graph/overview.
How do I get access to the Microsoft 365 API?
Self-serve for any developer who registers an app in Microsoft Entra ID, but tenant data needs user consent or admin consent.
Does the Microsoft 365 API have rate limits?
No single global limit: throttling thresholds vary by service and scenario (see the service-specific limits page) and return 429 with Retry-After.
Can I connect Microsoft 365 to my other tools without writing code against its API?
Yes. With Caddi you show the Microsoft 365 task once, the way you'd train a new hire, and Caddi builds it as verified code that runs across Microsoft 365 and the other tools the job touches. Where a step has no API, Caddi uses a secure, audited browser session in the same automation.
Do I need a developer to automate Microsoft 365 with Caddi?
No. There is no integration code for you to write or maintain. Every automation Caddi builds for Microsoft 365 is reviewed before it runs in production, and every run is logged.
Connect Microsoft 365 without the build.
Drop your work email and pick a time. We'll show you Caddi running your Microsoft 365 workflow end to end.