.htaccess Remove WWW from URL + Directories

Redirection code for both non-www => www and opposite www => non-www. No hardcoding domains and schemes in .htaccess file. So origin domain and http/https version will be preserved.

APACHE 2.4 AND NEWER

NON-WWW => WWW:

RewriteEngine On
RewriteCond %{HTTP_HOST} !^www\. [NC]
RewriteRule ^ %{REQUEST_SCHEME}://www.%{HTTP_HOST}%{REQUEST_URI} [R=301,L]

WWW => NON-WWW:

RewriteEngine On
RewriteCond %{HTTP_HOST} ^www\.(.*)$ [NC]
RewriteRule ^ %{REQUEST_SCHEME}://%1%{REQUEST_URI} [R=301,L]

Note: not working on Apache 2.2 where %{REQUEST_SCHEME} is not available. For compatibility with Apache 2.2 use code below or replace %{REQUEST_SCHEME} with fixed http/https.

---

APACHE 2.2 AND NEWER

NON-WWW => WWW:

RewriteEngine On

RewriteCond %{HTTPS} off
RewriteCond %{HTTP_HOST} !^www\. [NC]
RewriteRule ^ http://www.%{HTTP_HOST}%{REQUEST_URI} [R=301,L]

RewriteCond %{HTTPS} on
RewriteCond %{HTTP_HOST} !^www\. [NC]
RewriteRule ^ https://www.%{HTTP_HOST}%{REQUEST_URI} [R=301,L]

... or shorter version ...

RewriteEngine On
RewriteCond %{HTTP_HOST} !^www\. [NC]
RewriteCond %{HTTPS}s ^on(s)|offs
RewriteRule ^ http%1://www.%{HTTP_HOST}%{REQUEST_URI} [R=301,L]

WWW => NON-WWW:

RewriteEngine On

RewriteCond %{HTTPS} off
RewriteCond %{HTTP_HOST} ^www\.(.*)$ [NC]
RewriteRule ^ http://%1%{REQUEST_URI} [R=301,L]

RewriteCond %{HTTPS} on
RewriteCond %{HTTP_HOST} ^www\.(.*)$ [NC]
RewriteRule ^ https://%1%{REQUEST_URI} [R=301,L]

... shorter version not possible because %N is available only from last RewriteCond ...

I had the same problem (trouble stripping 'www' from URLs that point to a sub-directory on an add-on domain), but after some trial and error, this seems to work for me:

RewriteEngine on
RewriteCond %{HTTP_HOST} ^www\.(.*)$ [NC]
RewriteRule ^(.*)$ http://%1%{REQUEST_URI} [R=301,QSA,NC,L]