Important User Information: Remote access to EBSCO's databases is permitted to patrons of subscribing institutions accessing from remote locations for personal, non-commercial use. However, remote access to EBSCO's databases from non-subscribing institutions is not allowed if the purpose of the use is for commercial gain through cost reduction or avoidance for a non-subscribing institution. Free GIS for herpetologists: free data sources on Internet and comparison analysis of proprietary and free/open source software. Geographical Information Systems (GIS) have been used widely in zoology and ecology, particularly in herpetology. The use of spatially explicit analysis has increased during the last decade, with the consequent expansion of GIS application in ecology. During the last years, geo-information technology has been developed within the Free/Open Source Software (FOSS) community, resulting in new open source formats and several GIS packages. However, proprietary packages seem still to be the first choice for herpetologists, thus involving non negligible costs for GIS technology adoption. Additional costs arise from environmental data, which are usually expensive, worsening in the case of large study areas. An alternative solution is to use freely available data, despite a possible decrease of resolution. In this review, we aim to show the feasibility of spatial analysis within FOSS GIS packages, rank these packages using the number of available tools and list several data sources freely available on the Internet. We listed several websites providing the most important free data for spatial analysis, i.e. altitude and derived data, past, current and future climatic series data, and satellite derived data. We provide also a list of the most commonly used functions in GIS analysis and their availability in the six software compared in this study (ArcGIS, gvSIG, ILWIS, Quantum GIS, GRASS, and DIVA-GIS). The software gvSIG is the one with more functions (106) followed by Quantum GIS with 94 and GRASS with 84. Copyright of Acta Herpetologica is the property of Firenze University Press and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. For access to this entire article and additional high quality information, please check with your college/university library, local public library, or affiliated institution. Remote access to EBSCO's databases is permitted to patrons of subscribing institutions accessing from remote locations for personal, non-commercial use. However, remote access to EBSCO's databases from non-subscribing institutions is not allowed if the purpose of the use is for commercial gain through cost reduction or avoidance for a non-subscribing institution. Source.