Tiny Core Linux!

Arch Linux is an independently developed, i686- and x86_64-optimised Linux distribution targeted at competent Linux users. It uses pacman, its home-grown package manager, to provide updates to the latest software applications with full dependency tracking. Operating on a rolling release system, Arch can be installed from a CD image or via an FTP server. The default install provides a solid base that enables users to create a custom installation. In addition, the Arch Build System (ABS) provides a way to easily build new packages, modify the configuration of stock packages, and share these packages with other users via the Arch Linux user repository. »

Linux is a free operating system, and Puppy Linux is a special build of Linux meant to make computing easy and fast.

SliTaz GNU/Linux LiveCD operating system. "SliTaz is a free operating system, working completely in RAM and booting from removable media such as a cdrom or USB key. SliTaz is distributed as a LiveCD, and weighs less than 30MB. The system is quick and responsive, clean and robust. SliTaz is simple and intuitive, providing a lightweight, elegant desktop, detailed documentation and easy to use configuration tools."

Alpine Linux is a security-oriented, lightweight Linux distribution based on musl libc and busybox.

Porteus is a complete linux operating system that is optimized to run from CD, USB flash drive, hard drive, or other bootable storage media. It's small (under 300Mb) and insanely fast which allows you to start up and get online while most other operating systems are left spitting dust. Porteus comes in both 32 & 64 bit and aims to keep on the bleeding edge. It also supports several different languages and the user forum has language sections.

Slax is a modern, portable, small and fast Linux operating system with a modular approach and outstanding design. SLAX is a LiveCD Linux distribution based on Slackware . Despite its small size, Slax provides a wide collection of pre-installed software for daily use, including a well organized graphical user interface and useful recovery tools for system administrators.

Pearl Linux OS has been available for free download since 12/2014 with our first release simply titled Pearl Linux. It was based on the 14.04 released version of Ubuntu. That release was using the XFCE desktop environment. Since then we now offer the MATE, GNOME, LXDE and soon to come our own DE PearlDE which will be a mix of LXDE and XFCE4 desktops. As of the latest release Pearl OS 3.0 we are now maintaining our own repository on site. Also all tho far from ready, we are working on the new website. The forum ain't pretty but it is up and running for ya all to post any questions you may have. »

Damn Small Linux is a very versatile 50MB mini desktop oriented Linux distribution.

The Temple Operating System (TempleOS) is a free and open source, x86_64, non-preemptive, multi-tasking PC operating system.

MenuetOS is an Operating System in development for the PC written entirely in 32/64 bit assembly language. Menuet64 is released under proprietary license and Menuet32 under GPL. Menuet supports 32/64 bit x86 assembly programming for smaller, faster and less resource hungry applications.

Plop Linux is a small distribution built from scratch that can boot from CD, DVD, USB flash drive (UFD), USB hard disk or from network with PXE. It's designed to rescue data from a damaged system, backup and restore operating systems, automate tasks and more. You can use Plop Linux as Server and as Desktop Linux.

KolibriOS is a tiny yet incredibly powerful and fast operating system. This power requires only a few megabyte disk space and 8MB of RAM to run. Kolibri features a rich set of applications that include word processor, image viewer, graphical editor, web browser and well over 30 exciting games. Full FAT12/16/32 support is implemented, as well as read-only support for NTFS, ISO9660 and Ext2/3/4. Drivers are written for popular sound, network and graphics cards.

Macpup is a minimalist desktop Linux distribution based on Puppy Linux . It uses Enlightenment as the default window manager and provides a user interface resembling that of Apple's macOS .

Puppy Linux Documentation Wiki - it is a Wikka