1. A computer-implemented method for keyword searching, the method comprising: receiving a plurality of noisy keywords for a document collection; generating, by a server, tokens for a plurality of keywords in the document collection; merging the tokens to create an index; receiving a search query, wherein the search query includes at least one search phrase; receiving, for the at least one search phrase, an indication from a user specifying to perform one of a noisy phrase search or a noiseless phrase search; and searching the index for the at least one search phrase based on the indication received from the user.