DYMO Website
DYMO LabelWriter drivers and documentation
As of October 2017, these were the latest drivers for LabelWriter 400 and 450 series, including the 4XL:
Windows 7/8/8.1/10:DYMO Label Software v8.6.1
MacOS X 10.12 Sierra: DYMO Label Software v8.6.1
LabelWriter 450 or 450 Turbo: some printers manufactured after April 1, 2014 experienced unique problems. Download an updated driver.