U.S. Patent and Trademark Office
- Search Patents and Published Applications
- Index to the U.S. Patent Classification
- Classification tools
- Google Patent Search
- Pat2Pdf.org - patents are available in PDF format.
- The Lens - The Lens is building an open, integrative basis for Innovation Cartography. Specifically, the Lens serves nearly all of the patent documents in the world as open, annotatable digital public goods that are integrated with scholarly and technical literature along with regulatory and business data.
- PatentScope - provides access to international Patent Cooperation Treaty (PCT) applications in full text format on the day of publication. The information may be searched by entering keywords, names of applicants, international patent classification and many other search criteria in multiple languages.
- FreePatentsOnline.com - offers many of the same search features as the USPTO site, but with an easier-to-use design and with the patents displayed as PDFs.
International Patent Offices:
- How to Conduct a Preliminary U.S. Patent Search: A step by step strategy - USPTO (36 minutes)
- An introduction: Why search for patents? What is a patent? MIT (5:30)