TYPO3: detect browser language and redirect to appropriate language version of the website if not requesting /typo3/

.htaccess

# Redirect visitors to the root domain path (e.g. www.mywebsite.ch) to the appropriate language version
# Fallback to English version if no matching browser language defined
# Based on language version being at e.g. www.mywebsite.ch/de/

# language starts with DE
RewriteCond %{REQUEST_URI} !typo3
RewriteCond %{HTTP:Accept-Language} ^de [NC]
RewriteRule ^$ /de/[L,R=301]

# language starts with FR
RewriteCond %{REQUEST_URI} !typo3
RewriteCond %{HTTP:Accept-Language} ^fr [NC]
RewriteRule ^$ /fr/ [L,R=301]

# language starts with IT
RewriteCond %{REQUEST_URI} !typo3
RewriteCond %{HTTP:Accept-Language} ^it [NC]
RewriteRule ^$ /it/ [L,R=301]

# else redirect to the English version
RewriteCond %{REQUEST_URI} !typo3
RewriteRule ^$ /en/ [L,R=301]