Is there any API's to pull the story points count from the Jira?

[Nisarga.lokesh]

Am writing a java code using jira-rest-api to customise the jira. But am not getting how to pull the story points for each project.

[Lady Di]

If you are writing a code as part of a jira plugin - Better use Jira java api:

https://developer.atlassian.com/server/jira/platform/java-apis/

issue.setCustomFieldValue(StoryPoints) //set

issue.getCustomFieldValue(StoryPoints) //get

If we are talking about an external application, here is the description of the documentation for the REST API

https://developer.atlassian.com/server/jira/platform/updating-an-issue-via-the-jira-rest-apis-6848604/