This article is outdated. (January 2014) are listed in tables below for comparison purposes. The first table lists the company behind the engine, volume and ad support. The second table lists Search engines privacy aspects along with other technical parameters, such as whether the engine provides personalization (alternatively viewed as a filter bubble). The final table identifies the nature of the software being used as open source or proprietary.
Many search services are not listed, including historical ones that have gone obsolete.