Abstract: Systems and methods are provided to evaluate a search engine using search results retrieved from a plurality of different search engines. For example, a controller can randomly distribute a set of pre-formulated queries to a plurality of computers to query the search engines at random times to obtain search results and combine the search results to evaluate the completeness of a query result provided by a particular search engine. The controller may simulate the random queries from users using a set of computers and may reduce the burden on the search engines by spreading out the query activities over a period of time, such as a month.