Espacenet European Patent Office (EPO). The database of the European Patent Office includes European Patents (EP), Patent Cooperation Treaty worldwide patents (WO) and Japanese patents (PAJ) and patent applications in their original language. Espacenet has information on more than 30 million patents.
Free Patents Online Now offers chemical search. Through entry of chemicals via SMILES, the patent database can be searched using normalized chemical formulas. Patents can be downloaded as PDF.
Google Patent Search Covers patents made available by the USPTO from the 1790s to the middle of 2006. Search the full text of U.S. patents from the Google Patent Search homepage, or visit the Advanced Patent Search page to search by various criteria including patent number, inventor, and filing date. Does not include patent applications, international patents, or U.S. patents issued over the last few months. Patents can be downloaded as a PDF.