Extensions API - how to create custom 'form' send action

New Contributor

Hi fellow developers,


This is my first post here. I've searched the forums and the web throughly, but couldn't find a proper answer.


I'm looking to create an extension for the HubSpot CRM. An important feature is being able to send a custom text message from within HubSpot to my integrations' API.

So what it should look like:

- On a contact page, click a button to open a form-type window.

- Type in message, click done/send.

- The message gets sent to the API.


On the CRM Extensions API Overview page, I only see a static action, without any UI or custom field options, or an iFrame action. Obviously, I could build my own form somewhere else, and use the iFrame action, but this isn't ideal.


On the App marketplace, I see other developers have managed to integrate this exact feature. So I was wondering how they might've done this. Here's what I'm talking about:


The video there shows that upon the click of a button, the exact kind of form view I'm looking for pops up, within the HubSpot interface. Any ideas on how to implement this myself?


Thanks in advance,




1 Reply 1
HubSpot Moderator

Hey @philipvanwijk,


The HubSpot + WhatsApp Integration is using a browser extension that modifies our UI (Here's the setup instructions: WhatsApp HubSpot Integration Documentation). 


Currently, this is not offically supported and while we list them, HubSpot wouldn't certify the app