esp@cenet European Patent Office
International patents issued by a number of countries including US, UK and Japan. It allows Quick search (a search with keywords), Advanced search (search using any of the indexed fields), Number search (search using publication, priority or NPL reference number) and Classification search (browse the Classification System of the EPO).
USPTO United States Patent and Trademark Office
From the U.S. Patent and Trademark Office (PTO), a full-text database of U.S. patents from 1790 to the present. A second database at this site provides indexing and citations for U.S. patents. A TIFF reader is required for access to full screen images in the full-text database. A complete patentability search must consider other sources, including patents prior to 1976, foreign patents, and non-patent literature.