wp-calypso/desktop/desktop-config/config-development.json

{
	"build": "development",
	"calypso_config": "desktop-development",
	"server_port": 3000,
	"server_url": "http://calypso.localhost",
	"server_host": "calypso.localhost",
	"updater": {
		"downloadUrl": "https://apps.wordpress.com/desktop/",
		"apiUrl": "https://api.github.com/repos/Automattic/wp-desktop/releases",
		"delay": 2000,
		"interval": 600000
	},
	"debug": {
		"enabled_by_default": true,
		"namespace": "desktop:*",
		"clear_log": false,
		"colors": true
	}
}