The GeoAPI is a web delivered service platform delivering both data and functionality, enabling geographical information to be viewed on a map. Just as with the web service, the GeoAPI enables the integration in external web pages of the geoportail functionality. Although the options for data processing are limited compared with “real” office GIS software, some targeted queries and analyses are possible. A web GIS makes access to geographical information truly independent of platform, installation and location.

At  you can find a complete documentation of the GeoAPI.