WP Rest API, Not Showing JSON

I have the WP Rest API 2.0 plugin installed and I thought the default output is JSON, but when I run this:

MY-URL/wp-json/wp/v2/posts, I get back output that looks like HTML.

Is there something in the endpoint or the plugin settings that I need to add to make it JSON?

I also tried running this in Postman and only see JSON when I select the “pretty” options.

How can I get JSON?

Thank you for your answers in advance.