I don't think they disclose that info, and likely desire to avoid any contractual commitment to provide it. I have noticed over the last few years, that the information they provide is not constant, but for some unknown reason, lately it seems reliable. I hope it will continue to be reliable. The Greeks are one of the late arrivals of support (was spotty, but now "seems" more reliable). The BID/ASK/Volume/Open Interest/LAST have been the most reliable option attributes. My experience is with SPX. Checking just now, I see support for SPX options back to Dec 7, 2009!
Thank you. I may try them out. OptionsXpress told me they only kept 6 months of historical options data.
They go back to March 2012 for the stock and options for a penny stock $MEMP which was 18.50 on that date with 6 option strikes publishing bid/ask spreads with no volume traded at the time. This can then be played back second by second - it's crazy when you think of the power of their database. That is a huge amount of data which hedge funds pay millions of dollars to have so they can run analysis on. They give you 100K of paper money and you can trade stocks and options and see what happens to your strategy over time. You can fast forward to weeks/months to see what happens to your theta decay in seconds vs watching the markets trade. It's the execution and slippage you don't get to see as they fill you in between bid/offer.