We demonstrate a new powerful mashup tool called WETSUIT (Web EnTity Search and fUsIon Tool) to search and integrate web data from diverse sources and domain-specific entity search engines. WETSUIT supports adaptive search strategies to query sets of relevant entities with a minimum of communication overhead. Mashups can be composed using a set of high-level operators based on the Java-compatible language Scala. The operator implementation supports a high degree of parallel processing, in particular a streaming of entities between all data transformation operations facilitating a fast presentation of intermediate results. WETSUIT has already been applied to solve challenging integration tasks from different domains.