Stein is open-source, and can be accessed via the managed service or be self-hosted.
The most efficient and easy way to deploy a production-ready instance of Stein is via the official fully-managed service. A couple of clicks will get you a fast and reliable API. Not only will it save you hours of maintenance per month, but you’ll be supporting open source software and getting great service!
To get started, sign up at the Stein website.
Stein is fully open source. You may customise it to your needs, determine your functionality, and host it yourself.
If you're comfortable installing, maintaining and updating your own software, this is the place for you.
Check out the related section on installation and setup.