Web cache replacement algorithms have received a lot of attention during the past years. Though none of the proposed algorithms deals efficiently with all the particularities of the Web environment, namely, relatively weak temporal locality (due to filtering effects of caching hierarchies), heterogeneity in size and origin of request streams. In this paper, we present the CRF replacement policy, whose development is mainly motivated by two factors. The first is the filtering effects of Web caching hierarchies and the second is the intention of achieving a balance between hit and byte hit rates. CRF’s decisions for replacement are based on a combination of the recency and frequency criteria in a way that requires no tunable parameters. Categories and Subject Descriptors H.3.4 [Information Storage and Retrieval]: Systems and Software—World Wide Web (WWW) Performance Evaluation; C.4 [Performance of Systems]: Measurement Techniques, Modelling Techniques, Performance Attributes. K...