# Custom properties

Hubspot custom properties allow you to map non-standard data from your source app to Hubspot. Follow the instructions in the linked article to learn how to setup custom fields in your Hubspot instance: <https://knowledge.hubspot.com/properties/create-and-edit-properties>

## Custom property mapping in Middle

Within the action to update or create a contact in Hubspot, you can construct an array of key-value pair objects to map integrated data to your custom property.

#### Internal name

<figure><img src="/files/0t1MHhcSWMvHus0QT6CB" alt=""><figcaption><p>The internal name can also be found in your property settings</p></figcaption></figure>

You will need to enter the internal name as the key in Middle. To view the internal name of a property click the **\</>** code code icon to view or set the internal name for the property, with a maximum of 100 characters.

{% hint style="warning" %}
Once a property is created, the internal name cannot be edited
{% endhint %}

<figure><img src="/files/cB1j75LhnaI5jlWFmhmE" alt=""><figcaption><p>Example of a key-value pair object array mapping data to Hubspot custom properties</p></figcaption></figure>

To create this array, follow the below steps:

1. Create a new action node in your workflow and then select the action to create or update a contact in Hubspot
2. Click to create a new parameter under any of the three customer property arrays
3. Click to [construct an array](/middle-docs/building-workflows/workflow-parameters.md#advanced-parameters)
4. Add a new parameter within this array
5. Click to [construct an object](/middle-docs/building-workflows/workflow-parameters.md#advanced-parameters)
6. This will give you an object where you can add a [text box](/middle-docs/building-workflows/workflow-parameters.md#constant-and-calculated-values) to the custom field key and then map your data in the value

{% hint style="success" %}
This input parameter can accept all data types. If you receive a data type error in the workflow editor, you can feel free to ignore it.
{% endhint %}


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