Peter Urban, Xavier Defago and Andre Schiper Neko: A Single Environment to Simulate and Prototype Distributed Algorithms Designing, tuning, and analyzing the performance of distributed algorithms and protocols are complex tasks. A major factor that contributes to this complexity is the fact that there is no single environment to support all phases of the development of a distributed algorithm. This paper presents Neko, an easy to use Java platform that provides a uniform and extensible environment for various phases of algorithm design and performance evaluation: prototyping, tuning, simulation, deployment, etc. Keywords: simulation, prototyping, distributed algorithms, message passing, middleware, Java, protocol layers.