Container technology has revolutionized large scale cloud computing, and is now taking the HPC world by storm as well.
Singularity was born out of the need to properly containerize and support workflows related to artificial intelligence, machine/deep learning.
It is now possible to build an application on your desktop and run hundreds or even thousands of instances, without change, on any of the public clouds.
Singularity Community Edition is a thriving open-source project with users and contributors around the world.
Like most open source projects, releases are based on feature milestones and apparent stability of the development branches.
Singularity is used around the world at major universities, government institutions, and national research labs, and is considered the platform of choice by academia and commercial HPC centers.
More on who is using Singularity