Multilingual tools can benefit communities in which language barriers exist. Such tools can be developed easily by combining language services provided via standard interfaces in frameworks such as the Language Grid. However, designing such tools is more challenging than implementing them since they must be customized for the target community. To optimize tool designs, designers must consider stakeholder requirements, available services and design options in an iterative process. This paper shows how a community can design such a multilingual tool by parallel prototyping using Web services, presenting a case study of an izakaya, a Japanese local restaurant. In parallel prototyping, more than one prototype is created and tested simultaneously, and this approach enables the tool users to give clearer feedback. In the case study, two different hi-fidelity prototypes are created by combining available language services, and these are then evaluated in a real life situation, resulting in effective feedback for improving the tool design.