Yes, you're correct Maxim, I've a WURFL-based caching system that handles content compression.

If I understand you correctly, the headers nginx receive from the upstream proxied server are sent without avail of the 'charset utf-8;' directive in nginx.

I was wondering If nginx without third party modules would be able to append the charset portion of the Content-Type header with the correct charset. But then, the answer is no.

Thank you.