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Patents: A How-To-Find Guide

Information on locating full-text of patents granted worldwide.

Free patent search engines

The search tools on this page are free to use unless otherwise noted. They are arranged by geographic/jurisdiction focus.

United States


Other National Sites

These search tools cover patents from individual countries or limited coalitions of countries. All are free unless otherwise noted. Be aware: some sites are best searched in their native language. Even when English translations are available, they are often automatically machine-generated and may contain errors or inconsistencies.

Please note: many other patent websites will provide some free information and will provide additional search types or features for a fee. If a free search does not produce results, do not assume a patent does not exist. Free-access databases have use search engines of varying quality, and patent search terms can vary tremendously from country to country. If you are seriously considering applying for a patent, a free search can help you find out whether or not a similar patent already exists; however, first time patent applicants are strongly encouraged to consult some of the books for beginners listed on the How-to Books tab of this guide.

Patent Equivalents

A "patent family" can be defined as all patent equivalents for a single invention. All of the published patent applications from various countries and the subsequent granted patents on an invention are commonly referred to as patent equivalents. They are not “true equivalents” in that each country may have different regulations for filing and different interpretations of the invention. It may include multiple patents in some countries because of differences in patent laws. When applying for a U.S. patent, inventors will need to know of any “prior art” which includes similar foreign patents or patent equivalents.

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Heather Lewin
150 Parks Library
(515) 294.1004