Hosts various builds, such as ESXi 5.5 Update 1 .

Note: Even for the free version, you usually need to "register" for a license key in the "License & Keys" tab of your portal to generate a key for the 5.5 version.

Major hardware vendors like Dell , HP , and Lenovo often host customized ESXi 5.5 images designed for their specific server hardware. These are typically the easiest "official" versions to find.

For general use in a lab environment, community-maintained archives often host these legacy files:

Vendors like Dell Support and HPE often keep their custom-tailored ESXi 5.5 ISOs available on their own driver pages. These are often safer and more compatible with specific server models.

For legacy hardware testing, vintage lab environments, or proprietary appliances, the ESXi 5.5 ISO remains a necessary evil. But for any production or internet-facing role, upgrade to vSphere 6.7 (minimally) or 7.0/8.0. The security and stability gains are immeasurable.