In the context of the EC-funded project Instant Mobility, we have defined a comprehensive architecture for transport and mobility applications that aim to innovate by introducing future Internet technologies to this domain. We have defined an Internet-based 'multimodal travel platform' that provides information and services able to support new types of connected transport applications. The considered scenario is centered on multimodal travelers (both drivers and passengers). In this paper, we present the SM4T1 simulator, that we have designed and implemented to test the platform and to interact with it on behalf of multimodal travelers. SM4T is a fully agent-based simulator for multimodal travelers mobility. The application simulates the movements of travelers on the different transport networks (road and public transport) while taking into account the changes in travel times and the status of the networks.