This core plugin comes preinstalled to the Heroku CLI.

$ npm install -g @heroku-cli/plugin-apps
$ heroku COMMAND
running command...
$ heroku (-v|--version|version)
@heroku-cli/plugin-apps/2.6.0 linux-x64 node-v10.4.1
$ heroku --help [COMMAND]
USAGE
  $ heroku COMMAND
...

• heroku apps - creates a new app
• heroku buildpacks - add new app buildpack, inserting into list of buildpacks if necessary
• heroku config - set one or more config vars
• heroku domains - add domain to an app
• heroku drains - adds a log drain to an app
• heroku dyno - restart app dynos
• heroku features - disables an app feature
• heroku keys - add an SSH key for a user
• heroku labs - enables an experimental feature
• heroku maintenance - display the current maintenance status of app
• heroku notifications - display notifications
• heroku ps - list dynos for an app
• heroku releases - display the releases for an app