How to use the WordPress JSON API without changing permalink settings

rest-route-param.md

The rest_route parameter allows one to pass the JSON API route directly to WordPress rather than using the /wp-json base URL.

So: https://demo.wp-api.org/?rest_route=/wp/v2/posts vs https://demo.wp-api.org/wp-json/wp/v2/posts (which will 404 if you don't have a compatible permalink setup for your site).

Reference:

• https://github.com/WP-API/WP-API/blob/a674b60acd8ef6109cdd83ce6036c037d97c233f/CHANGELOG.md#L1211
• WP-API/WP-API#1489