OxygenOS!

A free and open-source operating system for smartphones and tablet computers, based on the Android mobile platform. It is the successor to the highly popular custom ROM CyanogenMod, from which it was forked in December 2016 when Cyanogen Inc. announced it was discontinuing development and shut down the infrastructure behind the project. Since Cyanogen Inc. retained the rights to the Cyanogen name, the project rebranded its fork as LineageOS.

Replicant is a distribution of Android that is 100% Free Software.

MIUI is a stock and aftermarket firmware for smartphones and tablet computers based on Android.

Mobile-optimized with the flexibility, ubiquity and stability of the Linux core and a cutting edge user experience built with the renowned Qt™ platform.

Windows 10 Mobile is a mobile operating system developed by Microsoft. Some features include : Live Tiles, Kid's Corner, Photos + SkyDrive, Rooms. It also allows you to Take your Word docs, Excel spreadsheets, PowerPoint presentations and OneNote notebooks on the road, and automatically upload every photo and video you take on your phone to SkyDrive for safekeeping (with a choice of full or lower resolution).

Resurrection Remix ROM is ultimately full featured, stable and combined with the best features of open source roms. We are also providing lot of awesome original Resurrection Remix ROM add-on s in the builds.

AOKP stands for Android Open Kang Project. It is a custom ROM distribution for many Android devices. It is mostly based off of AOSP.

Slim ROM is super-lightweight Android ROM for Samsung Galaxy phones, that's aimed at advanced users. Slim is designed to trim the fat down to the bare essentials and give you a fast and clean Android installation.

Tizen is an open source mobile and device operating system based on Linux developed by Samsung and Intel.

Paranoid Android provides a unique experience and ultimate customization for your Android device.

Plasma Mobile turns your phone into a fully open hacking device, just like a PC. You can join us to start building new mobile experiences now.

Papyros is a modern operating system which adheres to Google's Material Design guidelines and is based on Arch Linux .

A hardened open-source operating system based on Android with PaX, OpenBSD malloc and much other privacy/security features.