Standard Web search services, though useful, are far from ideal. There are over a dozen different search services currently in existence, each with a unique interface and a database covering a different portion of the Web. As a result, users are forced to repeatedly try and retry their queries across different services. Furthermore, the services return many responses that are irrelevant, outdated, or unavailable, forcing the user to manually sift through the responses searching for useful information. This paper presents the MetaCrawler, a fielded Web service that represents the next level up in the information "food chain." The MetaCrawler provides a single, central interface for Web document searching. Upon receiving a query, the MetaCrawler posts the query to multiple search services in parallel, collates the returned references, and loads those references to verify their existence and to ensure that they contain relevant information. The MetaCrawler is sufficiently lightweight to r...

The MetaCrawler Softbot is a parallel Web search service that has been available at the University of Washington since June of 1995. It provides users with a single interface with which they can query popular general-purpose Web search services, such as Lycos[6] and AltaVista[1], and has some sophisticated features that allow it to obtain results of much higher quality than simply regurgitating the output from each search

this article, we briefly outline the motivation for MetaCrawler and highlight previous work, and then discuss the architecture of MetaCrawler and how it enables MetaCrawler to perform well and to scale and adapt to a dynamic Internet.