.htaccess

Options FollowSymLinks
AddDefaultCharset utf-8

<IfModule mod_rewrite.c>
    RewriteEngine On

    # the main rewrite rule for the frontend application
    RewriteCond %{REQUEST_URI} !^/(backend/web|admin)
    RewriteCond %{REQUEST_URI} !^/(api/web|api)
    RewriteRule !^frontend/web /frontend/web%{REQUEST_URI} [L]

    # redirect to the page without a trailing slash (uncomment if necessary)
    #RewriteCond %{REQUEST_URI} ^/admin/$
    #RewriteRule ^(admin)/ /$1 [L,R=301]
    # the main rewrite rule for the backend application
    RewriteCond %{REQUEST_URI} ^/admin
    RewriteRule ^admin(.*) /backend/web/$1 [L]

    # redirect to the page without a trailing slash (uncomment if necessary)
    #RewriteCond %{REQUEST_URI} ^/api/$
    #RewriteRule ^(api)/ /$1 [L,R=301]
    # the main rewrite rule for the api application
    RewriteCond %{REQUEST_URI} ^/api
    RewriteRule ^api(.*) /api/web/$1 [L]

    # if a directory or a file of the frontend application exists, use the request directly
    RewriteCond %{REQUEST_URI} ^/frontend/web
    RewriteCond %{REQUEST_FILENAME} !-f
    RewriteCond %{REQUEST_FILENAME} !-d
    # otherwise forward the request to index.php
    RewriteRule . /frontend/web/index.php [L]

    # if a directory or a file of the backend application exists, use the request directly
    RewriteCond %{REQUEST_URI} ^/backend/web
    RewriteCond %{REQUEST_FILENAME} !-f
    RewriteCond %{REQUEST_FILENAME} !-d
    # otherwise forward the request to index.php
    RewriteRule . /backend/web/index.php [L]

    # if a directory or a file of the api application exists, use the request directly
    RewriteCond %{REQUEST_URI} ^/api/web
    RewriteCond %{REQUEST_FILENAME} !-f
    RewriteCond %{REQUEST_FILENAME} !-d
    # otherwise forward the request to index.php
    RewriteRule . /api/web/index.php [L]

    RewriteCond %{REQUEST_URI} \.(htaccess|htpasswd|svn|git)
    RewriteRule \.(htaccess|htpasswd|svn|git) - [F]
</IfModule>