[nlitsme]

To be clear, the real zlib lives on http://zlib.net/ The .org variant is basically typosquatting the name.

[eesmith]

This is z-lib.org, which is entirely different.

FWIW, zlib.org gives a

  <META HTTP-EQUIV="Refresh" content="0; url=http://www.zlib.net">

and its body contains:

  zlib.org is temporarily redirected to <a href="http://www.zlib.net">zlib.net</a>