The best open source alternative to CloudReady is Debian, which is both free and Open Source. If that doesn't suit you, our users have ranked more than 100 alternatives to CloudReady and loads of them is open source so hopefully you can find a suitable replacement. Other interesting open source alternatives to CloudReady are Linux Mint (Free, Open Source), Manjaro Linux (Free, Open Source), Fedora (Free, Open Source) and elementary OS (Free, Open Source).
Chromium OS is an open-source project, used primarily by developers, that aims to build an operating system that provides a fast, simple, and more secure computing experience for people who spend most of their time on the web. Chromium OS and...
MINIX is a POSIX-compliant Unix-like operating system based on a tiny microkernel running in kernel mode with the rest of the operating system running as a number of isolated, protected, processes in user mode.
illumos is a free and open-source Unix operating system. It derives from OpenSolaris, which in turn derives from SVR4 UNIX and Berkeley Software Distribution (BSD). illumos comprises a kernel, device drivers, system libraries, and utility software for system administration.