QGIS

"QGIS is an Open Source Geographic Information System. The project was born in May of 2002 and was established as a project on SourceForge in June of the same year. We've worked hard to make GIS software (which is traditionally expensive commercial software) a viable prospect for anyone with basic access to a Personal Computer. QGIS currently runs on most Unix platforms (macOS/OS X included) and Windows. QGIS is developed using the Qt toolkit (http://qt.io) and C++. This means that QGIS feels snappy to use and has a pleasing, easy to use graphical user interface.

QGIS aims to be an easy to use GIS, providing common functions and features. The initial goal was to provide a GIS data viewer. QGIS has reached that point in its evolution and is being used by many for their daily GIS data viewing and editing needs. QGIS supports a number of raster and vector data formats, with new support easily added using the plugin architecture.

 Supported raster formats include:

• Grass
• USGS DEM
• ArcInfo binary grid
• ArcInfo ASCII grid
• ERDAS Imagine
• SDTS
• GeoTiff
• Tiff with world file
• WMS, WCS

Supported vector formats include:

• ESRI Shapefiles
• PostgreSQL/PostGIS
• GRASS
• GeoPackage
• Spatialite
• Other OGR supported formats
• MSSQL
• Oracle
• WFS

QGIS includes scripting support for Python.

https://github.com/qgis/QGIS

http://www.qgis.org/en/site/

http://docs.qgis.org/testing/en/docs/pyqgis_developer_cookbook/

http://www.qgistutorials.com/en/docs/web_mapping_with_qgis2web.html