Selecting the appropriate patent database largely depends on the type of information you need. If you need to find a copy of a known patent, there are many places on the web where you can download PDFs. However, if you need to do a state-of-the-art or patentability search, here are some criteria you should considered when selecting a database.
Year coverage: Does the database included historical patents?
Currency: How often is the database updated? Most patent offices publish new patents on a weekly basis.
Country coverage: Does the database include patents from more than one country?
Classification: Does the database include current patent classification codes from the CPC, IPC or USPC systems?
The following websites are excellent sources of information on public and commercial patent databases.
The largest public patent database on the internet, Espacenet contains 100 million patent documents from more than 90+ countries including Canada and the U.S., plus 2 million records for non-patent literature cited in EPO search reports.
Explore 65 million patent documents from more than 51 regional and national patent offices. Major national collections include Canada, China, European Patent Office, Japan, Korea, Russia, the U.K and U.S.
SciFinder provides access to more than 100 years of chemistry and related science information through the combined coverage of Chemical Abstracts and MEDLINE. SciFinder includes patents from 65 patent issuing authorities worldwide. As of June 2013, approximately 23.5% of the records in SciFinder are patents.
SureChemBL is a public chemical patent database maintained by the European Bioinformatics Institute (EBI). It indexes chemical structures from full-text EP, JP, US and WO patent documents; bibliographic data from more than 90 countries is also searchable.