WordPress rest API get Posts parent by post ID

As posts can’t have parents, there is no endpoint to get the parent ID of a post.

However, pages can have parents, so the page endpoint should return a parent ID, among other things. So, by getting mysite.com/wp-json/wp/v2/pages, you should be able to get the parent attribute, which is “The ID for the parent of the object.” If you want just the parent, you could use _filter in your request.