RewriteEngine on
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME}\.html -f
RewriteRule ^(.*)$ $1.html
# Replace html with your file extension, eg: php, htm, asp
To add a trailing slash at the end of the URL
(for example: http://www.example.com/about-us/ to go to http://www.example.com/about-us.html)
RewriteEngine on
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME}\.html -f
RewriteRule ^([^/]+)/$ $1.html
# Forces a trailing slash to be added
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_URI} !(\.[a-zA-Z0-9]{1,5}|/)$
RewriteRule (.*)$ /$1/ [R=301,L]