Key-value stores (KVSs) are the most prevalent storage systems for large scale web services. As they do not have the structural complexities of RDBMSs, they are more efficient. In this paper, we introduce the problem of keyword search over KVSs and analyze its differences with keyword search over documents and relational databases. We propose a novel method called Keyword Search over Key-value stores (KSTORE) to solve the problem. Our user study using two real life data sets shows that KSTORE provides better ranking than the extended versions of document and relational database keyword search proposals and poses reasonable overheads. Categories and Subject Descriptors: H.2.0 [Database Management]: General General Terms: Algorithms, Designs, Performance