Intelligent Systems & Robotics

U.S. Patents & Trademarks Office (USPTO) 

The United States Patent and Trademark Office (USPTO) is the federal agency for granting U.S. patents and registering trademarks.

• PatFT - USPTO Patent Full Text and Image Database
• AppFT - USPTO Patent Application and Image Database
• TESS - Trademark Electronic Search System

European Patents

• Espacenet - Patent search

Other search engines

• Free Patents Online 
• Google Patents
• Patent Lens