Add a column on the left with sequential numbering in a csv table with Notepad++

• Click with the cursor to the very top left position
  Press Alt+C
  Select Text to Insert
  Type “,“
  Press OK
  

• Click with the cursor to the very top left position
  Press Alt+C
  Select Number to Insert
  Select Dec
  Set Initial Number to “0”
  Set Increase by to “1”
  Let Repeat be empty
  Set Leading to “None”
  Press OK
  

• Press Ctrl+H or go to Search/Replace
  Click Wrap around
  In the Find what field, enter a single space character
  Leave the Replace with field completely empty
  Ensure the Search Mode is set to Normal (not Regular expression)
  Press Replace All
  

• Press Ctrl+End
  Delete last entry of the first column
  (Do not delete the CRLF of the last row)