The free ESXi download (officially called ESXi Single Server) will experience a name change to VMware vSphere Hypervisor. For detailed information on the new and enhanced features in vSphere 4.1, see What’s New in vSphere 4.1.
Download VMware vSphere. Run fewer servers and reduce capital and operating costs using VMware vSphere to build a cloud computing infrastructure. ESX 4.1 ISO - Virtualisation May 07, 2015 VMware vSphere 4: Private Cloud Computing, Server and Data
Support for Legacy ESXi Versions
Dec 30, 2010 Downloads of "VMware vSphere Hypervisor (ESXi) 5.1" and
VMware vSphere 4: Private Cloud Computing, Server and Data
Vmware ESXi 4.1 Free License key - Alfred Tong Jan 12, 2012 install software on VMware ESXi 4.0/4 - download