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QGIS, formerly Quantum GIS, is a user friendly open source Geographic Information System (GIS) licensed under the GNU General Public License that runs on Linux, Unix, Mac OSX, and Windows and supports numerous vector, raster, and database formats and functionalities.

GRASS GIS (Geographic Resources Analysis Support System) is an open source, free software (FOSS) Geographical Information System (GIS) with raster, topological, vector, image processing, and visualization functionality. Used for geospatial data management and analysis, image processing, graphics/maps production, spatial modeling, and visualization, GRASS is currently used in academic and commercial settings around the world, as well as by many governmental agencies and environmental consulting companies. »

SAGA - System for Automated Geoscientific Analyses - is a Geographic Information System (GIS) software with immense capabilities for geodata processing and analysis. SAGA is programmed in the object oriented C++ language and supports the implementation of new functions with a very effective Application Programming Interface (API). Functions are organised as modules in framework independent Module Libraries and can be accessed via SAGA’s Graphical User Interface (GUI) or various scripting environments (shell scripts, Python, R, ...). »

MapWindow is a fully free and open source geographic information system project. It includes an open source programming component, MapWinGIS ActiveX, and an extensible desktop application that supports plug-ins written in .NET (C# and VB.NET). The most recent effort, MapWindow 6, includes a fully C# programming library that is intended to serve as an alternative to ESRIs ArcObjects platform.

Business mapping software (geographic information system) that delivers affordable, easy-to-use, professional mapping tools for mapping in these sectors: franchising, health care, business, territories, site selection, sales, marketing, banking, more

ArcGIS is geographic information system (GIS) software for visualizing, managing, creating, and analyzing geographic data. Using ArcGIS, you can understand the geographic context of your data, allowing you to see relationships and identify patterns in new ways.

gvSIG is a Geographic Information System (GIS), that is, a desktop application designed for capturing, storing, handling, analyzing and deploying any kind of referenced geographic information in order to solve complex management and planning problems.

uDig is a GIS software program produced by a community led by Canadian-based consulting company Refractions Research. It is based on the Eclipse platform and features full layered open source GIS. It is written in Java and released under GNU Lesser General Public License.

Supergeo Technologies Inc. is global leading GIS software & total solution provider. With series GIS products covering from desktop, mobile, server to developer SDK, SuperGIS has been utilized more than 100 different countries.

Professional desktop GIS supporting most ArcGIS (and other) data formats, enterprise spatial databases, 5,000 pre-defined coordinate systems, and built-in scripting IDE for customization and feature extensions.

Beautiful, User Friendly online mapping software that scales to big data.

What3words encodes geographic coordinates into 3 dictionary words (for example, the Statue of Liberty is located at planet.inches.most). what3words is different from other alphanumeric location systems and GPS coordinates in that it displays 3 words rather than long strings of numbers or letters. what3words has a website, apps for iOS and Android, as well as an API that enables bidirectional conversion of what3words address and latitude/longitude coordinates.Source: Wikipedia

MapET Spatial Feature Server is software that makes your geographic information (vector data) available to others in your organization and optionally anyone with an Internet connection. This is accomplished through web services, which allow a powerful server computer to receive and process requests for information sent by other devices. MapET Spatial Feature Server opens your GIS to devices that can connect to web services.

Easily Work With Location Data In Spreadsheets. GeoSheets lets you get comprehensive location lookup by state, neighborhood, and more with dead simple functions.