[arthurcolle]

I source option data from a combination of some paid APIs, some free sources. You can find a lot of data sitting around the internet if you're careful about it and respect robots.txt... Some people even pay for XIgnite and other crazy expensive data sources, but then have not secured their own endpoints (some SaaS operators have done this) so I scoop that data up too.

but as @marketgod suggests, you can definitely just use broker APIs, thats going to be the best bet for the most part and if you're price sensitive.