Use PatFT to search for U.S. patent grants, and AppFT to search for U.S. patent applications. Note that PatFT only allows for full-text searching back to 1976; to find patents granted before then, you must search by classification. Browse or search the Cooperative Patent Classification (CPC) database to find relevant classification schemes.
The worldwide database (from the European Patent Office) contains information on published patent applications and granted patents from over 100 patent-granting authorities. Can machine-translate patent documents.
Allows for full-text searching of patent grants and applications from the United States and from 100+ patent offices around the world.
The PATENTSCOPE database provides access to international Patent Cooperation Treaty (PCT) applications in full text format on the day of publication, as well as to patent documents of participating national and regional patent offices.
The United States Patent and Trademark Office (USPTO) recommends a Seven Step Strategy for conducting preliminary searches of U.S. patents and published applications using free online resources of the USPTO and its bi-lateral partner EPO (European Patent Office).
Seven Step Strategy Handout and Tutorial
To view the Seven Step Strategy in detail using a search example, review the USPTO's 7-Step U.S. Patent Search Strategy Guide handout
The Patent and Trademark Resource Center Program also provides a CBT (computer based training) tutorial with a detailed review of the Seven Step Strategy. The current CBT covers searching using Cooperative Patent Classification (CPC).