The HTTP output in ArcGIS Velocity allows you to send features and other text to an HTTP endpoint through POST requests. A request is sent for each output feature sent to the output.


An analyst configures an HTTP output to send features in a custom JSON format to a designated webhook.

Usage notes

  • When sending JSON as a POST body, wrap the JSON with the Text() Arcade expression to properly format the JSON.
  • When using the HTTP output, it is important to understand the velocity of the data. Each record sent to the output generates a separate request. This can quickly overload the capacity or rate-limiting settings of a web server. Use the HTTP output for incidents expected to occur infrequently.


ParameterDescriptionData type


The URL over which the output requests are sent.


POST body

The JSON Arcade expression.

Arcade Expression


The Content-Type header for outgoing requests.

  • Plain Text: text/plain
  • JSON: application/json
  • CSV: text/csv
  • XML: text/xml


URL Parameters

Optional URL parameters that are included in the URL of the HTTP request sent to the specified website.

While parameters can also be set in the URL parameter above, the URL parameters entered here as separate parameters override any matching parameter supplied in the URL parameter.

URL parameters defined in this parameter will always be URL encoded.

Key-Value Pair

Custom headers

Optional custom headers that are included in the HTTP request sent to the specified website. For example, custom headers can be used to specify a third-party API key or authorization header.

Key-Value Pair

Considerations and limitations

The web server must be externally accessible on the internet.