JetBrains MPS is a language development environment.
You can download the last stable version from here
Our current version is MPS 2019.3.
What is the Early Access Program (EAP)?
We at JetBrains believe that making good tools for developers should greatly rely on developers' opinions. Our Early Access Program lets the development community closely participate in discussions devoted to JetBrains MPS and influence the planning and development from the early stages onwards. We hope this EAP will be both valuable and exciting, just as EAP program for IntelliJ IDEA is. We highly appreciate your feedback and ideas!
It is important to distinguish EAP from pre-release software. Please note that the quality of EAP versions may at times be far below even usual beta standardsTHIS IS AN EARLY ACCESS VERSION OF THE PRODUCT. YOU EXPRESSLY ACKNOWLEDGE THAT THIS VERSION OF THE PRODUCT MAY NOT BE RELIABLE, MAY NOT WORK AS INTENDED AND MAY CONTAIN ERRORS. ANY USE OF THE EAP PRODUCT IS AT YOUR OWN RISK.
EAP Download page
You can download currently available MPS EAP builds from JetBrains MPS 20172020.2 1 EAP Download Page.