One popular PaaS (Platform as a Service) provider is Cloud Foundry. You can visit a public-facing version known as Pivotal Web Services at https://run.pivotal.io to discover options. It's also possible for you to build and set up your own local instance of Cloud Foundry using the open source tools found at https://github.com/cloudfoundry, but we won't go into that. Assuming that you have an account at run.pivotal.io, let's proceed by installing the Cloud Foundry CLI tool.
If we visit https://github.com/cloudfoundry/cli, we can find installation instructions for multiple platforms.
On a Mac system with Homebrew (http://brew.sh), all we have to do is type the following:
$ brew tap pivotal/tap $ brew install cloudfoundry-cli ...