The emergence of affordable mobile devices with rich interfaces and high-bandwidth wireless connectivity has revolutionized the mobile Web. However, such new trends also imply downloading larger data volumes from the Web, with considerable battery and, often, monetary costs that inevitably degrade user experience. The mobile Web calls for end-to-end data deduplication that is able to achieve both high precision and negligible computational cost on the battery-constrained client side. We propose dedup HTTP, a novel deduplication solution that leverages the generic approach of Cache-Based Compaction to achieve the above requirements. Using a full-fledged implementation of dedup HTTP with real workloads from popular Web sites, we obtained savings in traffic consumption of up to 94,5% when comparing to plain HTTP transfer.