Optsum data is an end of day index option summary for CBOE traded options in ^SPX, ^OEX, and ^VIX with volume traded, open interest, open, high, low and last sales prices for every series in chain.
1 minute or n-minute interval summaries including NBBO with size, OHLC prices, and trade volumes along with optional open interest and Calcs data (implied volatilities and Greeks)
End-of-day snapshot and 3:45PM ET snapshot for quotes, OHLC prices, and volume summaries along with optional Calcs data (implied volatilities and Greeks)