- Google Advanced Patent Search (PDFs available for free)
- U.S. Patents and Patent Applications -- Full-Text Images (1790 to date)
- U.S. Patent Number Search (full-text)
- Patent Lens
- Full-text of 7 million patent documents from US, Europe, Australia, WIPO, and counterparts in up to 60 countries.
- European Patent Office -- espacenet.com
- Free Patents Online
Download patents from the U.S. and the World Intellectual Property Organization (WIPO)in pdf or TIFF formats.
- International Patents
- Guide to Downloading Patent Copies on the Internet
Lists free web sites and software tools that allow you to download patents as PDF documents
- Patents and Other Links (from the British Library)
Gateway to a wealth of patent information on the web, concentrating on world-wide sources compiled by the British Lending Library -- databases, tutorials, associations, publications, manuals, document suppliers and many others!