Pros and Cons
Each patent search site has its pros and cons as can be seen in Table 1. For the most complete and current search of US Patents, we recommend using the USPTO site. Likewise, for the most complete and current search of European Patents, we recommend using Espacenet. If patent wrappers are desired, those are available from the USPTO and Espacenet sites.
|Site||US Pats/Apps||NonUS Pats/Apps||Other|
|USPTO.gov||Pat, App (Full)||None||US Pat Wrapper|
|Worldwide.espacenet.com||Pat, App (Full-)||Pat, App (Europe+)||Wrapper (Dossier)|
|Patents.Google.com||Pat, App (Full-)||Pat, App (International-)||Not Guaranteed|
|Scopus||Pat, App (Full-)||Pat, App (International-)||Links to USPTO, Espacenet|
|Key||minus (-) symbol = some patents or applications lacking|
|plus (+) symbol = additional regions|
Google Patents, on the other hand, does offer the convenience of one-stop searching of a broad set of sources. Espacenet offers similar convenience of searching for US and European patents. The USPTO site is the least feature-rich search engine. Historically, this was done deliberately to avoid competition with commercial search engines, although current search features are more user-friendly. Several commercial databases also include provisions for searching patents, but they generally link out to the USPTO and Espacenet sites. So, it comes down to how you value convenience vs completeness, and what kind of special information you may want.