I personally use a spreadsheet but I'm sure there are better way to do it.
Do you know any good websites/apps to do it?
I think you not needed a spreadsheet or anything else because in trading yes we make profit and losses but it is more on winning or profit if you use to trade well or lets we say that you have a good skills in trading we doesn't need it anymore it will just ruin your trade by being greedy if you lose more than profit in some circumstances.