> ## Documentation Index
> Fetch the complete documentation index at: https://loops.so/docs/llms.txt
> Use this file to discover all available pages before exploring further.
# Carrd integration
> Enable sign ups to Loops using a native Carrd form.
### Add a form to your Carrd site
1. Add a form to your site and select the **Custom** option.
2. Select **Send to URL** and paste in your form endpoint from the [Forms page in Loops](https://app.loops.so/forms).
3. Paste the form endpoint you copied from into the **URL** input in Carrd.
4. Change the **Method** to "AJAX" and the **Format** to "JSON".
Our form submission endpoint has rate limiting, so you will see an error in testing if you
submit more than once per minute or submit the same email twice.
### Customizing the form
In addition to collecting the email address, you can also collect any other contact property you want.
1. Follow Carrd's documentation to [add a new field to your form](https://carrd.co/docs/forms/setting-up-a-custom-form)
2. Determine your preference:
* A hidden field that is set to a static value
* A value that your user can set
3. Assign the field an "ID" matching the Loops API property name that you want to set. You can check the full list of your available properties from your [API Settings](https://app.loops.so/settings?page=api) page.
For example, if you want to set the User Group property, you would add a hidden field and set the ID to `userGroup`.
To add subscribers to specific [mailing lists](/contacts/mailing-lists), add a field with an ID `mailingLists`. The **Value** can be a single mailing list ID or if you want to add subscribers to multiple lists, a comma-separated list of IDs.
Mailing lists need to be marked **Public** in your [Lists settings](https://app.loops.so/settings?page=lists) in order for them to work in forms.