I'm getting the 404 but can't get an output about wp-slim-framework

[Botnary]

does your implementation looks like this ?

add_action('slim_mapping',function($slim){
    $slim->get('/nano/api/books/:id',function($bookId){
            echo $bookId;            
    });
});

how is your wordpress installed ? in a sub folder ?

[dcp3450]

Turns out it was the piece you pointed out. I figured it out right after I posted this. The instructions say, this:

add_action('slim_mapping',function($slim){
    $slim->get('/site/api/user/:u',function($user){
        printf("User is %s",$user);            
    });
});

but it doesn't say that if you change the default on the settings page you need to update the above code manually. That was my confusion.

[Botnary]

Is good it's working now :)