Does Hubspot webhook subscription support Custome created properties on contacts/companies? Or is there only support fot the Hubspot created properties?
The Webhooks APIdoes allow you to subscribe to custom properties you define! As the documentation notes, however:
If a customer's account doesn't have the property you specify in a subscription, you will not get any webhooks from that customer for that property.
To ensure that all of the accounts in which your app is installed have the desired custom property, you can create them with the Contact Properties API and the Company Properties API.
I think it would be very cool to be able to subscribe to the update the "Last modified date" field and then it would be easier to track custom properties.
Could the developers consider such an improvement to the API?
The Webhooks APIdoes allow you to subscribe to custom properties you define! As the documentation notes, however:
If a customer's account doesn't have the property you specify in a subscription, you will not get any webhooks from that customer for that property.
To ensure that all of the accounts in which your app is installed have the desired custom property, you can create them with the Contact Properties API and the Company Properties API.