Webhooks can be triggered by configuring the webhook destination in the system. The webhook destination can be configured to send data to any http endpoint. Both POST and GET endpoints are supported. The document describes the configuration and the format of the payload sent to the endpoint.

Webhook Configuration

Keep a webhook ready to work with. It can be simply simulated with a Python HTTP server by running python -m http.server 8080. Alternatively, you can use an online webhook provider, such as Webhook Site.

These providers may restrict the number of requests sent.

Creating a Webhook Connection on

Go to destinations on and create a new destination. Select Webhook as the destination. Webhook Selection On the next page, enter the name of the connection and paste the webhook URL. The picture below shows that we are using an online webhook provider. Additionally, select the method POST or GET depending on the HTTP method supported by the webhook provider. Click on the Next button to connect to the webhook, test the connection, and create it. Webhook Url

Setting up a Sync

  1. Supported Destination Modes

Webhook supports the following destination modes. Please refer to the Destination Sync Modes for more information on the different destination modes.

Destination ModeSupported

The picture below shows that we have selected Upsert destination sync mode. customer_id has been selected as the Primary Key for the Warehouse source. The source fields first_name, last_name, email, active have been mapped to the destination fields my_first_name, my_last_name, email, active respectively. Webhook Mapping

  1. Payload format for POST

The payload below includes the above mapped fields and _valmi_meta that describes the action _valmi_sync_op that can be be performed in the webhook server. Additionally, _valmi_row_num shows the row number of the source data, starting with index 1.

  "_message_id": 6,
  "_sync_mode": "upsert",
  "_type": "object",
  "payload": {
    "_valmi_meta": {
      "_valmi_row_num": 7,
      "_valmi_sync_op": "upsert"
    "my_first_name": "Jason",
    "my_last_name": "Haley",
    "email": "",
    "active": 1
  1. Payload format for GET

GET method flattens out the above json payload as request parameters. Below is the GET version of the http callback. "GET /?_valmi_meta__valmi_row_num=347&_valmi_meta__valmi_sync_op=upsert&my_first_name=Ryan&my_last_name=Salisbury& HTTP/1.1"

  1. Verifying loaded data on the Webhook

You can confirm the number of callbacks triggered from the Sync Runs Page. Webhook Runs The below image shows that we have received http callbacks on the webhook provider site. As we have chosen POST method, the JSON payload of the http callbacks is as described above. Webhook Data