Turn a list into a printable sheet of labels. Paste one label per block (blank line between multi-line addresses, or one per line), pick a common Avery-style layout, and print. Set your printer to 100% / actual size and no page scaling for the grid to line up. Nothing is uploaded.

Sheet layout

Separator

Repeat first label to fill the sheet

Labels

Layouts use the standard label dimensions for each product code, on Letter or A4 as noted; small differences between printer models mean you should print one test page on plain paper and hold it over a real label sheet before committing. Choose "actual size" (not "fit to page") in the print dialog. Everything runs on your device.