This paper presents a compact cluster computer, called “UCC (Ubiquitous Computing Cluster)”, which provides a cost-effective prototyping environment for design and test of ubiquitous computing applications. We achieve extremely small size, low power consumption and low cost by employing COTS (Commercial Off-The-Shelf) embedded CPUs. We also present an application of UCC to fingerprint verification using phase-based image matching and its performance analysis. Our experimental observation shows that the cluster is useful for prototyping practical application programs targeted at network-connected embedded CPUs.