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# Elements of the flow - HTTP trigger

The `HTTP trigger` triggers a flow when an HTTP call is made to the URL generated in the element.

⚠️ The use of the HTTP trigger and in particular the optional components requires knowledge of URL and query strings.

**Configuration**

1️⃣ The URL that must be called to start the flow can be found in the field highlighted in blue.

2️⃣ Optionally, further information can be transmitted with the URL. In the selection field for the input, you can specify whether this information is to be obtained from the header or the query parameters.

3️⃣ The key that characterises the additional information can be defined here.

4️⃣ The `Required` function can be used to specify whether the transmission of the additional information is essential for the further execution of the flow. If this field is ticked, the flow is cancelled and none of the subsequent elements are executed if the information is not transmitted.

5️⃣ The `ADD INPUT` button can be used to add further information, as described under 2️⃣ to 4️⃣.

6️⃣ You can define your own HTTP response with status code, content type and body using the `Send custom HTTP response` function.


![](https://storage.crisp.chat/users/helpdesk/website/91fefd8b4b0ac000/flowhttptriggeren_yemqdr.png)