This is a module that is distributed with tengine which is a distribution of Nginx that is used by the e-commerce/auction site Taobao.com. This distribution contains some modules that are new on the Nginx scene. The ngx_http_concat module is one of them.

The module is inspired by Apache's modconcat. It follows the same pattern for enabling the concatenation. It uses two ?, like this:

http://example.com/??style1.css,style2.css,foo/style3.css

If a third ? is present it's treated as version string. Like this:

http://example.com/??style1.css,style2.css,foo/style3.css?v=102234

The new repo is at https://github.com/taobao/nginx-http-concat.