Search the full text of patents 1976 - present; patents issued 1790 - 1975 are searchable by patent number or issue date. The Patent Application Database contains all patent applications published since 2001.
Espacenet
A free patent search tool, including 80 million patent documents from the European Patent Office, the USPTO, and other countries worldwide, searchable by full text.
The Lens
A patent search database including records from patent offices worldwide. It also allows searching of gene sequences.
TRAIL: Technical Report and Image Library
Use the TRAIL search tool to find and access digital versions of U.S. technical reports published prior to 1975.
Science.gov
Science.gov is a search engine providing access to millions of pages of scientific information provided by federal agencies.