Using Square:

• Log Into Squareup.com 
• On the left side should be a series of square buttons. (you may have to click the 3 small lines near the top to make the menu appear) 
• Click the one that says “Customers”
• This should show you a list of customers with whom you have conducted business.
• On the upper, right side should be a button that says “Import / Export” – click this button
• Choose “Export Customers”
• Then choose “All Customers”
• It should take a moment to build your export
• The next screen should say ” A CSV file containing your customers is ready for download”
• Click “Download” and save it to your computer

That’s it!  You should now have a file on your computer with your customer list.  Feel free to modify any information or delete any columns for privacy.