Hi @Lovisa,
Depending on which version of JMP you are using you can import the JSON file directly into JMP using the File Open command.
 
Import JSON File-->Open
 
Import JSON Red Triangle Option Tall Format
Select the "Tall guess" option from the red triangle menu option.
And after clicking OK you get the JMP data table with a source script that you can reuse as needed for importing additional files.
Open(
	"$Desktop/example_json.json",
	JSON Settings(
		Stack( 0 ),
		Row( "/root/externalData" ),
		Col(
			"/root/externalData/orderNumber",
			Column Name( "orderNumber" ),
			Fill( "Use Once" ),
			Type( "Numeric" ),
			Format( {"Best"} ),
			Modeling Type( "Continuous" )
		),
		Col(
			"/root/externalData/batchNumber",
			Column Name( "batchNumber" ),
			Fill( "Use Once" ),
			Type( "Character" ),
			Format( {"Best"} ),
			Modeling Type( "Continuous" )
		),
		Col(
			"/root/externalData/partNumber",
			Column Name( "partNumber" ),
			Fill( "Use Once" ),
			Type( "Numeric" ),
			Format( {"Best"} ),
			Modeling Type( "Continuous" )
		)
	),
	JSON Wizard( 0 )
)
 
cheers,
Stan