I would not recommend to use the Yahoo or Google apis to get option prices. Some of the bid/ask prices are completly wrong and some expiration dates are missing. I created an option scanner as a side project and found about this bad data quality the hard way.
It's a good place to get solid data but it's quite expensive. EOD history for SPX alone is $250 apparently. All symbols are $2500 and my understanding is that this is just CBOE options? Is CME not in there?
iVolatility told me it would be ~$1000 for EOD chains + IV & Greeks since 1990 - just for SPX. CBOE is partners with iVolatility so I imagine their data is decent, but I can't bring myself to drop that much on it for a simple personal project.
I would not recommend to use the Yahoo or Google apis to get option prices. Some of the bid/ask prices are completly wrong and some expiration dates are missing. I created an option scanner as a side project and found about this bad data quality the hard way.