With Espacenet you can search titles of over 50 million patents from 71 countries. The video below shows how to search for patents using Espacenet.
Commercial databases offer easier searching with more whistles and bells than the freely available databases.
There are other very sophisticated databases that the law school does not subscribe to, such as:
See patent offices for individual countries for more databases.
You will want to search by CLASSIFICATION in order to get more results than a keyword search, and for increased accuracy.