Yes, but only on a limited basis as the platform demo is solely intended to demonstrate the functionality of the TWS and its API. As background, the TWS demo simulates a “live” stream of simulated market data using previous week's ticks and does not offer the historical data necessary to populate Ninja Trader charts requiring a combination of streaming and historical data.
Once your live IBKR account is approved and funded a paper trading account may be requested, the market data subscriptions to which will accommodate full testing of the Ninja Trader application.
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