Third-Party Storage Integration in Microsoft Teams

05/29/2025

Microsoft Teams allows users to integrate third-party cloud storage providers by modifying the default storage options from OneDrive and SharePoint. This capability enables files that are dragged and dropped into the Teams chat or message compose area to be stored in a third-party storage service. Using the Microsoft Teams JavaScript client library (TeamsJS), third-party apps can capture these files through the getDragAndDropFiles API and then upload them to their own cloud storage.

To enable this feature, the latest version of the TeamsJS SDK is required, along with a properly configured app manifest and the app ID of the third-party storage provider. When a file is dragged and dropped, it is temporarily cached in Teams before being fetched by the third-party app and uploaded to its storage. This seamless integration enhances flexibility for businesses using external storage solutions within the Teams environment.

Included Features

Bots
Message Extensions

Interaction with Messaging Extension

msgext-thirdparty-storage

Prerequisites

Microsoft Teams is installed and you have an account
.NET SDK version 6.0
dev tunnel or ngrok latest version or equivalent tunnelling solution

Run the app (Using Microsoft 365 Agents Toolkit for Visual Studio)

The simplest way to run this sample in Teams is to use Microsoft 365 Agents Toolkit for Visual Studio.

Install Visual Studio 2022 Version 17.14 or higher Visual Studio
Install Microsoft 365 Agents Toolkit for Visual Studio Microsoft 365 Agents Toolkit extension
In the debug dropdown menu of Visual Studio, select Dev Tunnels > Create A Tunnel (set authentication type to Public) or select an existing public dev tunnel.
In the debug dropdown menu of Visual Studio, select default startup project > Microsoft Teams (browser)
Right-click the 'M365Agent' project in Solution Explorer and select Microsoft 365 Agents Toolkit > Select Microsoft 365 Account
Sign in to Microsoft 365 Agents Toolkit with a Microsoft 365 work or school account
Set Startup Item as Microsoft Teams (browser).
Press F5, or select Debug > Start Debugging menu in Visual Studio to start your app
In the opened web browser, select Add button to install the app in Teams

If you do not have permission to upload custom apps (uploading), Microsoft 365 Agents Toolkit will recommend creating and using a Microsoft 365 Developer Program account - a free program to get your own dev environment sandbox that includes Teams.

Setup

Note these instructions are for running the sample on your local machine, the tunnelling solution is required because the Teams service needs to call into the bot.

Run ngrok - point to port 3978
```
ngrok http 3978 --host-header="localhost:3978"
```
Alternatively, you can also use the dev tunnels. Please follow Create and host a dev tunnel and host the tunnel with anonymous user access command as shown below:
```
devtunnel host -p 3978 --allow-anonymous
```
Setup for Bot

In Azure portal, create a Azure Bot resource.
- For bot handle, make up a name.
- Select "Use existing app registration" (Create the app registration in Microsoft Entra ID beforehand.)
- If you don't have an Azure account create an Azure free account here
In the new Azure Bot resource in the Portal,
- Ensure that you've enabled the Teams Channel
- In Settings/Configuration/Messaging endpoint, enter the current https URL you were given by running the tunnelling application. Append with the path /api/messages

Clone the repository

git clone https://github.com/OfficeDev/Microsoft-Teams-Samples.git

If you are using Visual Studio
- Launch Visual Studio
- File -> Open -> Project/Solution
- Navigate to samples/msgext-thirdparty-storage/csharp folder
- Select TeamsMsgextThirdpartyStorage.csproj or TeamsMsgextThirdpartyStorage.slnfile
Update the appsettings.json configuration for the bot to use the MicrosoftAppId, MicrosoftAppPassword, MicrosoftAppTenantId generated in Step 1 (App Registration creation). (Note the App Password is referred to as the "client secret" in the azure portal and you can always create a new client secret anytime.)
- Set "MicrosoftAppType" in the appsettings.json. (Allowed values are: MultiTenant(default), SingleTenant, UserAssignedMSI)
- Set "BaseUrl" in the appsettings.json as per your application like the ngrok forwarding url (ie https://xxxx.ngrok-free.app) after starting ngrok and if you are using dev tunnels, your URL will be like: https://12345.devtunnels.ms.
Run your bot, either from Visual Studio with F5 or using dotnet run in the appropriate folder.
This step is specific to Teams.
- Edit the manifest.json contained in the appPackage folder to replace your Microsoft App Id (that was created when you registered your bot earlier) everywhere you see the place holder string <<YOUR-MICROSOFT-APP-ID>> (depending on the scenario the Microsoft App Id may occur multiple times in the manifest.json)
- Edit the manifest.json for validDomains with base Url domain. E.g. if you are using ngrok it would be https://1234.ngrok-free.app then your domain-name will be 1234.ngrok-free.app and if you are using dev tunnels then your domain will be like: 12345.devtunnels.ms.
- Zip up the contents of the appPackage folder to create a manifest.zip (Make sure that zip file does not contains any subfolder otherwise you will get error while uploading your .zip package)
- Upload the manifest.zip to Teams (In Teams Apps/Manage your apps click "Upload an app to your org's app catalog". Browse to and Open the .zip file. At the next dialog, click the Add button.)
- Add the bot to personal/team/groupChat scope (Supported scopes)