OneDrive Authentication: OAuth 2.0 and Microsoft Graph (2026)

Authentication overview

OneDrive integrates with the Microsoft ecosystem, leveraging Microsoft Graph as its unified API endpoint. Authentication for OneDrive applications is primarily handled through OAuth 2.0, an industry-standard protocol for delegated authorization. This approach allows third-party applications to access OneDrive resources on behalf of a user, without requiring the application to store the user's Microsoft credentials directly. Instead, applications obtain access tokens from Microsoft's identity platform, which are then used to authorize API requests.

The core principle behind OneDrive's authentication model is to provide secure, granular access to files and folders while maintaining user control over data permissions. Developers register their applications with Microsoft's identity platform (formerly Azure Active Directory), define the necessary permissions (scopes), and implement an OAuth 2.0 flow to acquire consent from the user. Once consent is granted, the application receives an access token that grants temporary access to the specified resources.

This system ensures that applications only have the permissions they explicitly request and that users can revoke access at any time. The integration with Microsoft Graph means that authentication patterns established for other Microsoft 365 services, such as Outlook or SharePoint, are largely transferable to OneDrive, streamlining development for those already familiar with the Microsoft Graph API.

Supported authentication methods

OneDrive, through the Microsoft Graph API, supports various OAuth 2.0 flows to accommodate different application architectures and user interaction requirements. The choice of flow depends on the application type (e.g., web application, mobile app, daemon service) and the level of user interaction available.

For most interactive applications that access user data, the Authorization Code Grant Flow is the recommended and most secure option. This flow involves redirecting the user to Microsoft's login page to grant consent, after which an authorization code is returned to the application. The application then exchanges this code for an access token (and optionally a refresh token) at the token endpoint, typically using a client secret (for confidential clients) or Proof Key for Code Exchange (PKCE) (for public clients like mobile apps).

Getting your credentials

To integrate with OneDrive, developers must register their application within the Microsoft identity platform. This process generates the necessary application credentials, primarily a Client ID (also known as Application (client) ID) and, for confidential clients, a Client Secret. These credentials identify your application to Microsoft's identity platform.

Registration steps:

1. Access the Microsoft Entra admin center: Navigate to the Microsoft Entra admin center and sign in with a Microsoft account.
2. Register a new application: Under 'Identity' > 'Applications' > 'App registrations', select 'New registration'.
3. Provide application details:
   • Name: A user-facing name for your application.
   • Supported account types: Choose who can use your application (e.g., 'Accounts in any organizational directory (Any Microsoft Entra ID directory - Multitenant) and personal Microsoft accounts (e.g., Skype, Xbox)' for broader access).
   • Redirect URI: The URL where the authentication response will be sent after the user grants consent. This is critical for the Authorization Code Grant flow. Specify the platform type (e.g., 'Web', 'Mobile and desktop applications').
4. Record Client ID: After registration, the 'Overview' page will display your 'Application (client) ID'. This is your unique identifier.
5. Generate Client Secret (for confidential clients): For web applications or other confidential clients, navigate to 'Certificates & secrets' > 'Client secrets' and select 'New client secret'. Provide a description and expiration. Record the secret value immediately, as it cannot be retrieved later.
6. Configure API permissions: Under 'API permissions', select 'Add a permission' > 'Microsoft Graph' and choose the delegated or application permissions your app requires (e.g., Files.ReadWrite, Files.ReadWrite.All). Grant admin consent if necessary for organizational accounts.

The Client ID and Client Secret are fundamental to initiating authentication requests and should be treated as sensitive information. For public clients (like mobile or desktop apps), PKCE is used instead of a client secret to secure the authorization code exchange.

Authenticated request example

After successfully obtaining an access token through an OAuth 2.0 flow, you can use it to make authenticated requests to the Microsoft Graph API for OneDrive. The access token is typically included in the Authorization header of your HTTP requests as a Bearer token.

Here's an example using a hypothetical JavaScript fetch request to list the contents of the root folder in OneDrive:

const accessToken = 'YOUR_ACCESS_TOKEN'; // Obtained via OAuth 2.0 flow

async function listOneDriveRootFolder() {
  try {
    const response = await fetch('https://graph.microsoft.com/v1.0/me/drive/root/children', {
      method: 'GET',
      headers: {
        'Authorization': `Bearer ${accessToken}`,
        'Content-Type': 'application/json'
      }
    });

    if (!response.ok) {
      if (response.status === 401) {
        console.error('Authentication failed: Access token expired or invalid.');
        // Implement token refresh logic here
      } else {
        throw new Error(`HTTP error! status: ${response.status}`);
      }
    }

    const data = await response.json();
    console.log('OneDrive Root Folder Contents:', data.value);
  } catch (error) {
    console.error('Error fetching OneDrive data:', error);
  }
}

listOneDriveRootFolder();

This example demonstrates how the Authorization: Bearer YOUR_ACCESS_TOKEN header is crucial for authenticating the request. Replace YOUR_ACCESS_TOKEN with an actual access token obtained from Microsoft's identity platform. The specific endpoint /me/drive/root/children is part of the Microsoft Graph API documentation for listing DriveItem children.

Security best practices

Implementing secure authentication for OneDrive integrations requires adherence to several best practices to protect user data and maintain application integrity:

• Use the Authorization Code Grant Flow with PKCE: For public clients (mobile, desktop, single-page applications), always implement PKCE (Proof Key for Code Exchange) with the Authorization Code Grant Flow. PKCE mitigates the risk of authorization code interception attacks. For confidential clients (web applications), ensure your client secret is securely stored and transmitted.
• Protect Client Secrets: If your application uses a client secret, never embed it directly in client-side code, mobile apps, or desktop applications. Store secrets securely on your server and retrieve them only when needed. Consider using environment variables, Azure Key Vault, or other secure secret management services for production deployments.
• Scope Permissions Minimally: Request only the minimum necessary permissions (scopes) for your application to function. For example, if your app only needs to read files, request Files.Read instead of Files.ReadWrite or Files.ReadWrite.All. This limits the potential impact if your application's access token is compromised. Review the Microsoft Graph permissions reference carefully.
• Handle Access Tokens Securely:
  • Short-lived access tokens: Access tokens are typically short-lived (e.g., 60 minutes). Implement proper refresh token handling to obtain new access tokens without re-authenticating the user.
  • Refresh token security: Refresh tokens are long-lived and highly sensitive. Store them securely (e.g., encrypted in a secure database for server-side apps, or in secure storage on mobile devices). Never expose refresh tokens client-side.
  • Token validation: If your application acts as a resource server, validate incoming access tokens (e.g., verify signature, issuer, audience, expiration) before granting access to resources.
• Implement HTTPS Everywhere: Ensure all communication between your application, Microsoft's identity platform, and the Microsoft Graph API occurs over HTTPS to prevent eavesdropping and man-in-the-middle attacks.
• Regularly Rotate Client Secrets: For confidential clients that use client secrets, establish a policy for regularly rotating these secrets to reduce the window of opportunity for compromise.
• Implement Error Handling and Logging: Robust error handling for authentication failures and comprehensive logging can help identify and diagnose potential security issues or misconfigurations promptly.
• Stay Updated: Keep up-to-date with the latest security recommendations and SDK versions from Microsoft for the Microsoft Graph API and identity platform.