$ npm install -g parse-server mongodb-runner
$ mongodb-runner start
$ parse-server --appId APPLICATION_ID --masterKey MASTER_KEY --databaseURI mongodb://localhost/test
You can use any arbitrary string as your application id and master key. These will be used by your clients to authenticate with the Parse Server.
That's it! You are now running a standalone version of Parse Server on your machine, with a locally-hosted Mongo DB as well.