[mzfr]

Quickbook - https://quickbooks.intuit.com/in/

They have a decent interface, press the "clock in" button and the time starts. Whenever you want you can "clock out". You can see the "total time" report as well as the invoices or payout made.

The only downside I see is that when you "clock in" you get a small input box in which you can choose to write whatever work you've done or you are doing. The issue is that box is super small and you can't really see that much in it. So there is lot of scrolling involved.