Substrate is a base application and set of libraries for making Google App Engine python development easier. It includes a base app with management script, testing already set up, a set of common helper functions (agar), and a serialization library (restler). It also comes with common libraries like webapp2 and pytz ready to go.
Substrate is based on best practices for Google App Engine python learned in developing several real-world applications with many users.
We are tired of seeing App Engine frameworks languish unsupported. For that reason, Substrate is NOT a framework. It is a base application with a set of libraries and helpers. No more, no less.
Substrate is mostly a packaging of other libraries, which have their own licenses. Original code in Substrate is under the MIT License.