The historical data you can get from multiple places, but getting real time streaming data for all symbols is not available for free. Actually, looks like they are limiting to only 15 symbols, which sucks.
- Each account can have up to one concurrent websocket connection.
- Trades, quotes and minute bars are supported.
- Subscription is limited to 30 channels at a time for trades and quotes (T. and Q.). This limit is temporary and we may support more channels in the future.
This number refers to how close these five exchanges to the NBBO published by the SIPs. The main exchanges are missing from their list(Nasdaq, NYSE, Arca, bats/edge).