> For the complete documentation index, see [llms.txt](https://guides.clickatell.com/flow/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://guides.clickatell.com/flow/action-nodes/action-nodes-is-null.md).
# Is Null
With the *Is Null* action node, you can verify whether a variable exists (i.e., is it a real value or a NULL value) and define what action follows - either route the customer to a new step in the workflow or trigger a new workflow.
For example, you can verify whether an expected response parameter from an API is available in the response received.
{% hint style="success" %}
This node is typically used after an [*API Integration*](/flow/action-nodes/action-nodes-api-integration.md) node to check whether a variable exists within the returned payload.
{% endhint %}
Setup an Is Null node
---
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