# Webhook
The **Webhook** tool allows you to trigger a MESA workflow from a third-party service. It can similarly be thought of like a notification. It lets a third-party service start a workflow in MESA when something happens in your third-party service.
With Webhook, you can create a chain reaction of events that allows you to focus more on your store than work on repetitive tasks.
## Set up a Webhook trigger
When creating a new workflow, you can select the **Webhook** tool as the trigger.
## Add a Webhook URL to your app that you want to connect with
Hit the Copy button to copy the link from the Webhook URL field and add it to your app in order for MESA to receive notifications from your third-party application.
## Send data to a webhook
After adding the Webhook URL to your app, data coming from your third-party application is sent to MESA's Webhook trigger in the form of a JSON payload.
## Manually run your webhook
You will want to manually run your Webhook trigger by sending a notification from your third-party application.
To check the payload coming from your third-party application, click on the **Activity** tab of your workflow in the MESA dashboard. Then expand the recent run of your workflow, click the 3 vertical dots on the right side of the **Webhook** text, and then click **Request Details**.
On subsequent steps, you can create variables that reference the data that is received in the Webhook trigger. For example, you can use the variable: `{{webhook.team_domain}}`
## Limitations
You are unable to send data back to the request. MESA can only receive data coming from the third-party application.
Variables will not be selectable from the Webhook trigger from the Variables menu on subsequent steps. You will need to manually create the variables following the format: `{{webhook.team_domain}}`
## Examples and use cases
**Webhook** provides the ability to integrate or provide additional capabilities with third-party applications that are currently not supported in MESA. For example, you can trigger a workflow using a Slack command.
After creating an app in Slack and adding a command, you can add the Webhook URL from your MESA workflow to the settings of your Slack command.
When messaging on Slack, you can type in the command and hit Enter to trigger the workflow in MESA.
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