Free patent search engines
The search tools on this page are free to use unless otherwise noted. They are arranged by geographic/jurisdiction focus.
Patent Public Search
The patent search tool of the U.S. Patent and Trademark Office. Provides full-text for U.S. patents.
USPTO Web Patent Databases This link opens in a new window
Contains links to the various databases of the U.S. Patent and Trademark Office. Provides full-text of patents from 1976 to the present and full-page images for patents starting in 1790. Patent images can only be searched by issue date, patent number, and classification. PatFT, AppFT, Pub EAST, and Pub WEST will be retired in October 2022.
Espacenet This link opens in a new window
Free access to millions of patent documents, containing information about inventions and technical developments from around the world.
The Lens: Patent Search
The Lens covers over 100 million patent documents from around the world. Includes classification searching and quick access to patent family information. Patents identified using the Lens can then be tracked down elsewhere if full text is not available in the Lens.
Google Patent Search
This is exactly what it sounds like – Google's patent database. It offers the ability to search through U.S. patents by patent number, inventor, keywords, date, classification number, or patent type. It also includes patent applications and international patents. Use Advanced Search form for specialized searches: https://patents.google.com/advanced
Patent search tool from the World Intellectual Property Organization (WIPO). Includes cross-lingual information retrieval and machine translation for several languages. Searches worldwide patents and links to documents in their national databases.
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.
African Regional Intellectual Property Organization (ARIPO) Search System
The African Regional Intellectual Property Organization (ARIPO) regional IP database includes information on patents, industrial designs, utility models, copyright and plant varieties from 20 African countries. ARIPO also works with member states to provide IP protection for traditional knowledge.
Canadian Patent Database
The Canadian Patent Database contains all Canadian patents (both applications and granted patents) since 1924. Contains only bibliographic data, titles and images. No abstracts or claims data are available for patents granted prior to August 15, 1978.
CNIPA Patent Search and Analysis
The China National Intellectual Property Administration (CNIPA) offers a free search engine for Chinese patent information. Click "English" for the English language version of the site.
Japan Platform for Patent Information (J-PlatPat)
Provides information on Japanese patents, utility models, designs, and trademarks. Machine-generated English translations are available.
Korea Industrial Property Rights Information Services (KIPRIS)
Covers domestic and foreign industrial property information such as patents, utility models, trademarks, and designs owned by the Korean Intellectual Property Office.
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.
Many patent documents, or at least their abstracts, are automatically translated into English using automated machine (computer) translations. If this is insufficient or a translation does not exist, the European Patent Office offers a fee-based translation service for Chinese, Korean, and Japanese patents.
EPO Patent Translation Service
Fee-based EPO service for ordering human translations of patent documents from Japanese, Korean or Chinese into English or German.
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.