OpenStack is a free and open-source software platform for cloud computing, mostly deployed as infrastructure-as-a-service (IaaS), whereby virtual servers and other resources are made available to customers.
License: Open Source
OpenStack is an open-source cloud computing platform that provides a high degree of customization and control over infrastructure, but requires significant expertise to manage. In contrast, Google App Engine is a fully managed platform that offers seamless integration and automatic scaling, making it ideal for developers looking for simplicity and ease of use.