The Online Patent Search: Do not waste your time developing a product that has already been patented by someone else. It pays to learn how to do a quick patent search online. There are many good patent search sites and we have listed a few of them for you.
Our favorite is FreePatentsOnline.com. The link to the search page is http://www.freepatentsonline.com/search.html. There is an overview and tutorial at http://research.freepatentsonline.com/help#patent-searching-overview.
Google Patents is also popular – https://patents.google.com/. Google has basic instructions on their support site – https://support.google.com/faqs/answer/7049475?hl=en&ref_topic=6390989.