Create a flowchart similar to flowchart in gojs, and connect custom HTML forms to each process step( UML diagram)

I want to build similar to flowchart , also I should able to build html form and connect html form to process step, is it possible to do this with goJS.

For example: we want to create uml kind of diagrams to represent the process flow and each process flow we collect some data using html forms, is it possible to create html form and connect with uml flow process stops.

if this can be achieved, we are planning to buy this plugin for our new project.

Yes, when a node is selected, or just when the user clicks it, you can show some HTML with details about the node. This could allow people to edit some of those details too.

Each such display of details and way that you let users edit them is very application-specific.

Each Node has a node data object that is a plain JavaScript Object with whatever properties your app needs. It is this object whose properties you would display in your HTML panel. And it is those properties that you would modify by calling the Model.set method so that the rest of the diagram, including the Node being edited, can update itself.

Furthermore, as an expediency to get you started, GoJS offers a Data Inspector as an extension. It shows a list of properties and lets the user edit their values. Examples:
https://gojs.net/latest/extensions/DataInspector.html
https://gojs.net/latest/samples/orgChartEditor.html

But in the long run most apps want to implement their own custom HTML for showing and editing each of their types of nodes. And maybe links too.