Install cURL from cURL website .

From the command line, enter the following cURL command:

// on macOS or Linux
curl -H 'Content-Type: application/json' -d '{"text": "Hello World"}' <YOUR WEBHOOK URL>
// on Windows
curl.exe -H "Content-Type:application/json" -d "{'text':'Hello World'}" <YOUR WEBHOOK URL>
If the POST succeeds, you must see a simple 1 output by curl.
Check the Teams client for the new card posted.
Prerequisite: Installation of PowerShell and familiarization with its basic usage.
To post a message to the webhook with PowerShell, follow these steps:
From the PowerShell prompt, enter the following command:
Invoke-RestMethod -Method post -ContentType 'Application/Json' -Body '{"text":"Hello World!"}' -Uri <YOUR WEBHOOK URL>
If the POST succeeds, you must see a simple 1 output by Invoke-RestMethod.
Check the Teams channels associated with the webhook URL. You can see the new card posted to the channel. Before you use the connector to test or publish your app, you must do the following:
Include two icons.
Modify the icons portion of the manifest to the file names of the icons instead of URLs.
All native Adaptive Card schema elements, except Action.Submit, are fully supported.
The supported actions are Action.OpenURL, Action.ShowCard, and Action.ToggleVisibility.
To send Adaptive Cards through an Incoming Webhook, follow these steps:
Set up a custom webhook in Teams.
Create Adaptive Card JSON file using the following code:
   "type":"message",
   "attachments":[
         "contentType":"application/vnd.microsoft.card.adaptive",
         "contentUrl":null,
         "content":{
            "$schema":"http://adaptivecards.io/schemas/adaptive-card.json",
            "type":"AdaptiveCard",
            "version":"1.2",
            "body":[
                "type": "TextBlock",
                "text": "For Samples and Templates, see [https://adaptivecards.io/samples](https://adaptivecards.io/samples)"
The properties for Adaptive Card JSON file are as follows:
The "type" field must be "message".
The "attachments" array contains a set of card objects.
The "contentType" field must be set to Adaptive Card type.
The "content" object is the card formatted in JSON.
Test your Adaptive Card with Postman:
Test the Adaptive Card using Postman to send a POST request to the URL, created to set up Incoming Webhook.
Paste the JSON file in the body of the request and view the Adaptive Card message in Teams.
Use Adaptive Card code samples and templates to test the body of POST request.
Rate limiting for connectors
Application rate limits control the traffic that a connector or an Incoming Webhook is permitted to generate on a channel. Teams track requests using a fixed rate window and incremental counter measured in seconds. If more than four requests are made in a second, the client connection is throttled until the window refreshes for the duration of the fixed rate.
Transactions per second thresholds
The following table provides the time based transaction details:
Time in seconds
Maximum allowed requests
A retry logic with exponential back-off can mitigate rate limiting for cases where requests are exceeding the limits within a second. Refer HTTP 429 responses to avoid hitting the rate limits.
// Please note that response body needs to be extracted and read 
// as Connectors do not throw 429s
    // Perform Connector POST operation     
    var httpResponseMessage = await _client.PostAsync(IncomingWebhookUrl, new StringContent(content));
    // Read response content
    var responseContent = await httpResponseMessage.Content.ReadAsStringAsync();
    if (responseContent.Contains("Microsoft Teams endpoint returned HTTP error 429")) 
        // initiate retry logic
These limits are in place to reduce spamming a channel by a connector and ensures an optimal experience to users.
See also
Webhooks and connectors
Create Incoming Webhooks
Create Outgoing Webhooks
Rate limiting for Teams bots messages
Build tabs with Adaptive Cards
Format cards in Microsoft Teams
Adaptive Cards
App manifest schema for Teams