Hello @ZSuiteTester
Based on the information you’ve provided, I can provide the following responses, in @ibuchanan 's absence.
Here, In the UI only the some fields are displaying.
That’s correct, as that’s how the screen scheme has been configured for that view of that issue type of that project. That is how Jira works.
But in the API, I m getting all the field along with some unwanted custom field.
Yes, that would expected, depending on which endpoint you used and what parameters you supplied. That’s how the API works.
And also based on the project type the displaying custom fields also change.
That’s correct, as each project can have its own custom screen scheme, custom issue types and therefore custom views of those issue types. That’s how Jira works.
I want list of fields which available all the issueType with irrespective of Epic, Story, sub-task or custom IssueType
That not really possible, since the ‘list of fields’ can be different for each issue type and none of that takes into account which of those fields are displayed through all the possible custom screens that issue type is using, and all of this can also be totally different per project. What you ‘want’ is a very, VERY, VERY non-trivial thing.
[bunch of JSON]
Where did that JSON come from? What does it mean? What are you expecting someone to do with it?
To me it sounds like you don’t fully understand how Jira works and the complexity of how the UI arrived at a particular view, but you want to somehow ‘extract’ an aspect of that, then replicate it in some other ‘UI’ using something or other (you don’t say what) and you’re asking someone here to explain it all. That’s like asking someone here to explain how a space ship works.
This is a community of Developers who can only provide assistance with specific programming problems. Nobody here can answer the sort of broad, non-specific questions as you’re asking.
I suggest you spend some time learning how Jira works and all the functions that combine together that result in the UI displaying a particular scenario to the user before you consider trying to replicate that.
Have fun on your learning journey