Yahoo Finance is the best tool. I like to trade options but I haven't found the best tool yet. I often follow Yahoo Options, I think this is the best tool and it is free. Although it is delayed 15 minutes as real-time price, I can get all contracts of many expirations and based on changing price.
Steps to follow:
Search a ticker and go to the Options section
There are 2 viewing types: List and Straddle. I often look at on Straddle section to compare between CALL and PUT.
In the expiration select box, I often visible the second or third week from current, it is less losing (this is my expiriense)
Key to focus: change and open interest, it is important to trade options
However, Yahoo Options don't support comparing change along days (I will note next article)
Summary, Yahoo Options is the best free tool to follow trading options.