.htaccess

<IfModule mod_rewrite.c>

    RewriteEngine On

    # Remove www from url
    RewriteCond %{HTTP_HOST} ^www\.(.+)$ [NC]
    RewriteRule ^ http%2://%1%{REQUEST_URI} [L,R=301]

    # Removes trailing slashes (prevents SEO duplicate content issues)
    RewriteCond %{REQUEST_FILENAME} !-d
    RewriteRule ^(.+)/$ $1 [L,R=301]

    # Change for specific system
    RewriteRule ^editor /molcalc [R=301,L]

    # Rewrite url for parameters, and keep GET query string
    # RewriteCond %{REQUEST_FILENAME} !-f
    # RewriteRule ^([^/\.]+)/([^/\.]+)/([^/\.]+)$ index.php?a=$1&b=$2&c=$3&%{QUERY_STRING} [L]

    # RewriteCond %{REQUEST_FILENAME} !-f
    # RewriteRule ^([^/\.]+)/([^/\.]+)$ index.php?a=$1&b=$2&%{QUERY_STRING} [L]

    # RewriteCond %{REQUEST_FILENAME} !-f
    # RewriteRule ^([^/\.]+)$ index.php?a=$1&%{QUERY_STRING} [L]

    # Removes access to the system folder by users.
    # Additionally this will allow you to create a System.php controller,
    # previously this would not have been possible.
    # 'system' can be replaced if you have renamed your system folder.
    # RewriteCond %{REQUEST_URI} ^system.*
    # RewriteRule ^(.*)$ /index.php/$1 [L] 

    # Checks to see if the user is attempting to access a valid file,
    # such as an image or css document, if this isn't true it sends the
    # request to index.php
    RewriteCond %{REQUEST_FILENAME} !-f
    RewriteCond %{REQUEST_FILENAME} !-d
    RewriteRule ^(.*)$ index.php?request=$1&%{QUERY_STRING} [L]

</IfModule>