1, the patent search website of the European Patent Office
This is a free patent literature database.
2. United States Patent and Trademark Office
It contains all patent documents published by the US Patent Office since 1790.
3. Chartered Electronic Library of Japan Patent Office
domestic
China National Intellectual Property Administration patent information retrieval system
It contains all the invention patents, utility model patents and design patents since 85 years, and can download the patent description within 100 pages. It is the most authoritative patent retrieval system in China.