There is no App. Stop Looking for an app for everything. There is stuff that you need to do in a simple way. All you need is a Demat account and Microsoft Excel. You can go for Polaris office or Liber Office if not excel. But that's all you need.
The fact that you are looking for an app shows you are looking for a quick fix. Paper trading is not a 3 or 4 days work. It takes years to develop profitable attitude to markets.
When I started in 2009, I blew my account several time. It is in 2012 that I started paper trading.
This is a glimpse of my paper trading back in 2012. You can see that I did it day after day in after market hours. Let me assure you that this went on till 2017 March. Day in Day out till I understood the attitude for trading. I still wasn't ready.
Here are some more excel sheets I created as I was refining my system.
Did you see. I could not miss a day. I had to record every stoploss. Every target. And if my strategy wasn't working then why it wasn't working and had to start from a scratch. And then I understood what is required. Analyzing data for what is working and what is not. Am I hitting too many stop loss or my targets are low. Is it right sticking to a loss or sticking to profit. Should I exit mid way. When to exit mid way. What kind of trading is suiting my needs. All of this after 5 years of paper trading and doing job side by side.
Now I am not saying that you will have to do the same or devote same time. There are far intelligent people then me who have achieved their paper trading goals in lesser time frame. But it needs patience. To see things fail and evolve. By asking that there is some app for it, you are going in all wrong.
Today when I trade with real money, I still use the same trading account and Microsoft excel. Nothing else. No fancy app or tool. Here is a glimpse of my latest month. It's just a part of my whole trading sheet but it is real. Profit/Loss figure are real. Max profit is what I would have gained from my strategy. Profit/Loss is what I gained or loss and that means I exited based on my understanding or took an early stop loss or exit.
Hope it helps.