Apache .htaccess configuration for auto-appending `.php` filename extension.

.htaccess

RewriteEngine on
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ $1.php [L,QSA]

# The two RewriteCond rules are boilerplate, they make sure files that exist
# on the server (CSS, JS, images, etc) will not have their URLs rewritten and
# be served directly.

# The RewriteRule captures all remaining URL requests, and adds a .php to the end.
#   The [QSA] flag ensures about.php does not become about.php.php.