https://www.theoptionslab.com

Usage:

[endpoint]/options/[ticker]   or 
[endpoint]/options/[ticker]?length=[number]

Example:

[endpoint]/options/aapl
[endpoint]/options/msft
[endpoint]/options/goog
[endpoint]/options/amzn
[endpoint]/options/aapl?length=1
[endpoint]/options/msft?length=2
[endpoint]/options/goog?length=3
[endpoint]/options/amzn?length=4