GFF provides free top of the book market data depending on your data feed:
Tradovate (CQG) — free market data for all CME Bundle.
DxFeed — free market data for CME instruments only.
If you'd like to trade instruments on additional exchanges such as CBOT or NYMEX, you can subscribe to those feeds directly through your platform.
Note: Gold and Silver are listed under COMEX, not CME, so they are included in the free data when trading via Tradovate.