Canadian Patents DatabaseThis database lets you access 93 years of patent descriptions and images. You can search, retrieve and study more than 2,140,000 patent documents.
Espacenet Patent SearchEspacenet offers free access to more than 80 million patent documents worldwide, containing information about inventions and technical developments from 1836 to today.
Free Patents OnlineBasically free full-text and/or images of patents from a variety of sources worldwide. Includes combined search option so you can search U.S., U.S. patent applications, European Patents, Japanese Patents (abstracts only), and WIPO. Also has a new chemical patent search feature. Be sure to check coverage for each database prior to searching.