URL Single Without Permalink
http://your_site/?_embed=1&rest_route=/wp/v2/posts/

JSON API fix 404
# API Rewrite rules
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule "^api/(.*)$" "/index.php?json=$1&%{QUERY_STRING}" [L]
</IfModule>
# END API Rewrite rules