List of free, open source smartphone operating systems

Updated: December 2, 2025

I'm beginning to experiment with these operating systems using old/cheap phones to evaluate whether they can be daily drivers in the future when it's time for a phone upgrade. The first testing I've done is with Ubuntu Touch. I'd like to move away from closed-source big vendor smartphone operating systems. The most interesting devices might be a Fairphone running Ubuntu Touch, postmarketOS, or a recent Google Pixel with GrapheneOS.

Devices

This is an incomplete list of devices commonly supported by above mobile operating systems. There are many more but these seem to be more recent. For the most recent phone support, consider Ubuntu Touch on Fairphone or an Android-based OS on whatever you have.