spx ndx etc are from nasdaq totalview, futures only brokers will have to buy the data. any equity brokers would have the index data for free real time.
open an AMP futures account with $500 or $1k and subscribe to CME futures data first level for $12 per month
get a demo CFD account and you can have free charting for many assets. try CMC markets https://www.cmcmarkets.com/en-gb/trading-platforms