Evaluations of the hazardous Earth environment and its effects on space systems are often hampered by the lack of comprehensive tools to access numerical models and data in an integrated environment. In order to help spacecraft engineers perform rapid analyses of environmental problems and to guarantee reliable results, ESA commissioned the development of the SPace ENVironment Information System (SPENVIS), a user-friendly WWW interface (available at http://www.spenvis.oma.be/) to models, tools and data describing the various aspects of the space environment and its hazardous effects. SPENVIS is conceived as a set of building blocks which are connected through a dynamic HTML interface. This design approach facilitates extensions and updates of the system with new models and tools, provides a flexible navigation through the many applications incorporated in the system and incorporates a protocol to interconnect with other services and tools, such as NASA's Space Ionizing Radiation Environments and Shielding Tools (SIREST). SPENVIS is based on internationally recognized standard models and methods in many domains. It uses an orbit generator to produce orbital point files necessary for many different types of problems. The radiation environment models in SPENVIS cover the Earth's radiation belts, cosmic rays and solar energetic particles. Fluxes and fluences derived from these models are used to calculate ionising and non-ionising dose, degradation of solar cells and single event effects for simple shielding configurations or in combination with a sectoring analysis. A Geant4-based Monte Carlo tool (Mulassis) for doses and pulse height analyses is available as well.