Although we try not to talk too much about it, many users of Varnish Cache actually use it "because it is the easiest way to get a C layer in our web stack".

Others are proud creators developing web sites in it using both VCL (which is compiled into C) and C directly through VMODs or Inline-C in VCL. More:

* https://www.varnish-cache.org/docs/trunk/users-guide/vcl-inl...

* https://www.varnish-cache.org/docs/trunk/reference/vmod.html

* https://www.varnish-cache.org/vmods

* https://www.varnish-cache.org/trac/wiki/VCL