GEOS - GEOS (Geometry Engine - Open Source) is a C++ port of the Java Topology Suite (JTS).
GDAL - Geospatial Data Abstraction Library (GDAL) is a computer library that serve as a translator library for raster and vector geospatial data formats.
Mapzen Tangram-ES - C++ library for rendering 2D and 3D maps using OpenGL ES 2 with custom styling and interactions
Mapnik Vector Tile - Mapnik C++ implemention of Mapbox Vector Tile specification.
Vector Tiles Producer - Command line tool in C++ to creates vector tiles for a given area at chosen zoom levels using a Mapnik XML.
libGeoTiff - Manipulate TIFF based interchange format for georeferenced raster imagery.
Orfeo ToolBox - Orfeo TooLBox (OTB) is an open-source C++ library for remote sensing images processing, distributed under the CeCILL-v2 licence.
ITK - ITK is an open-source, cross-platform system that provides developers with an extensive suite of software tools for image analysis.
RSGISLib - The Remote Sensing and GIS software library (RSGISLib) is a collection of tools for processing remote sensing and GIS datasets. The tools are accessed using Python bindings or an XML interface.
OSRM (Open Source Routing Machine) - High performance routing engine written in C++, designed to run on OpenStreetMap data. Services available: Nearest, Route, Table, Match, Trip, Tile.
OpenOrienteering Mapper - OpenOrienteering Mapper is a software for creating maps for the orienteering sport.
TauDEM - Terrain Analysis Using Digital Elevation Models (TauDEM) software for hydrologic terrain analysis and channel network extraction.
osgearth - A free open source C++ geospatial toolkit.
dreich_algorithm - Algorithm for extracting channel networks from high resolution topographic data.
LASzip - Quickly turns bulky LAS files into compact LAZ files without information loss.
laz-perf - Alternative LAZ implementation for C++ and JavaScript.
entwine - Entwine is a data organization library for massive point clouds, designed to conquer datasets of hundreds of billions of points as well as desktop-scale point clouds.
OpenDroneMap - OpenDroneMap is a tool to postprocess drone, balloon, kite, and street view data to geographic data including orthophotos, point clouds, & textured mesh.
S2 Geometry - Computational geometry and spatial indexing on the sphere.
TIN Terrain - A command-line tool for converting heightmaps in GeoTIFF format into tiled optimized meshes.
tippecanoe - Build vector tilesets from large collections of GeoJSON features.
Selene - A C++14 image representation, processing and I/O library.
Pronto Raster - C++ library for geographical raster data analysis.
valhalla - Open Source Routing Engine for OpenStreetMap.
Halide - Halide is a programming language designed to make it easier to write high-performance image processing code on modern machines.
gdalcubes - gdalcubes is a library to represent collections of Earth Observation (EO) images as on demand data cubes (or multidimensional arrays).
hydroflow - Compute drainage orders in drainage basins using Strahler and Shreve methods.
Python
Shapely - A library for manipulation and analysis of geometric objects in the Cartesian plane.
Pyproj - python interface to PROJ4 library for cartographic transformations
Rtree - A wrapper of libspatialindex providing spatial indexing features for Python GIS.
OSMnx - Python package that lets you download spatial geometries and construct, project, visualize, and analyze street networks from OpenStreetMap's APIs.
xarray - xarray (formerly xray) is an open source project and Python package that aims to bring the labeled data power of pandas to the physical sciences, by providing N-dimensional variants of the core pandas data structures.
mapboxgl-jupyter - Use Mapbox GL JS to visualize data in a Python Jupyter notebook.
Cartopy - A library providing cartographic tools for python for plotting spatial data.
geoalchemy - Using SQLAlchemy with spatial databases.
Pyncf - Pure Python NetCDF file reading and writing.
chupaESRI - ChupaESRI is a Python module/command line tool to extract features from ArcGIS Server map services.
geojsonio.py - Open GeoJSON data on geojson.io from Python. geojsonio.py also contains a command line utility that is a Python port of geojsonio-cli.
Ogcserver - Python WMS implementation using Mapnik.
RSGISLib - The Remote Sensing and GIS software library (RSGISLib) is a collection of tools for processing remote sensing and GIS datasets. The tools are accessed using Python bindings or an XML interface.
Scikit-image - Scikit-image is a collection of algorithms for image processing.
pyWPS - An implementation of the Web Processing Service standard from the Open Geospatial Consortium. PyWPS is written in Python. It enables integration, publishing and execution of Python processes via the WPS standard.
pyCSW - Fully implements the OpenGIS Catalogue Service Implementation Specification (Catalogue Service for the Web). Initial development started in 2010 (more formally announced in 2011). The project is certified OGC Compliant, and is an OGC Reference Implementation.
urbansim - New version of UrbanSim, a platform for modeling metropolitan real estate markets.
OSMnet - Tools for the extraction of OpenStreetMap street network data.
rio-hist - Histogram matching plugin for rasterio.
Verde - Verde is a Python library for processing spatial data (bathymetry, geophysics surveys, etc) and interpolating it on regular grids (i.e., gridding).
gpdvega - gpdvega is a bridge between GeoPandas and Altair that allows to seamlessly chart geospatial data.
LANDSAT-Download - Automated download of LANDSAT data from USGS website.
USGS API - USGS is a python module for interfacing with the US Geological Survey's API.
som-tsp - Solving the Traveling Salesman Problem using Self-Organizing Maps.
Centroids - This application reads a valid geojson FeatureCollection and returns a valid geojson FeatureColleciton of centroids.
sentinelsat - Search and download Copernicus Sentinel satellite images.
PyPostal - Python bindings to libpostal for fast international address parsing/normalization.
ts-raster - ts-raster is a python package for analyzing time-series characteristics from raster data. It allows feature extraction, dimension reduction and applications of machine learning techniques for geospatial data.
LT-ChangeDB - Scripts to extract spectral change information from LandTrendr data to a geodatabase.
pymap3d - Python 3D coordinate conversions for geospace ecef enu eci.
YATSM - Yet Another Timeseries Model (YATSM) is a Python package for utilizing a collection of timeseries algorithms and methods designed to monitor the land surface using remotely sensed imagery.
untiler - Stitch image tiles into larger composite TIFs.
pyroSAR - A Python Framework for Large-Scale SAR Satellite Data Processing.
RIOS - Raster I/O Simplification. A set of python modules which makes it easy to write raster processing code in Python.
thunder - Thunder is an ecosystem of tools for the analysis of image and time series data in Python.
eo-box - Earth observation processing framework for machine learning in Python.
lidar - Terrain and hydrological analysis using digital elevation models (DEMs).
geemap - A Python package for interactive mapping with Google Earth Engine, ipyleaflet, and ipywidgets.
pydeck - High-scale spatial rendering in Python, powered by deck.gl.
Java
Geotools - GeoTools is an open source Java library that provides tools for geospatial data.
GeoServer - GeoServer is open source server for sharing geospatial data.
GeoWebCache - a Java web application used to cache map tiles coming from a variety of sources such as OGC Web Map Service (WMS). It implements various service interfaces (such as WMS-C, WMTS, TMS, Google Maps KML, Virtual Earth) in order to accelerate and optimize map image delivery. It can also recombine tiles to work with regular WMS clients.
Geonetwork - GeoNetwork is a catalog application to manage spatially referenced resources.
JTS Topology Suite - JTS Topology Suite is an API of 2D spatial predicates and functions.
GeOxygene - Provide an open framework which implements OGC/ISO specifications for the development and deployment of GIS applications.
Gisgraphy - Open source framework that offers the ability to do geolocalisation and geocoding via Java APIs or REST webservices.
MapFish Print - The purpose of Mapfish Print is to create reports that contain maps (and map related components) within them. The project is a Java based servlet/library/application based on the mature Jasper Reports Library.
asgbook - Implementation of GIS/RS features in Java. Its also the code accompanying the book "Automating the Analysis of Spatial Grids" by Valliappa Lakshmanan.
LuciadLightspeed - A Java library that provides the foundations for advanced geospatial analytics applications
jpostal - Java/JNI bindings to libpostal for fast international street address parsing/normalization.
Photon - Photon is an open source geocoder built for OpenStreetMap data. It is based on elasticsearch.
GraphHopper Routing Engine - GraphHopper is a fast and memory efficient Java routing engine, released under Apache License 2.0. By default it uses OpenStreetMap and GTFS data, but it can import other data sources.
GeoWave - It provides geospatial and temporal indexing on top of Accumulo, HBase, BigTable, Cassandra, and DynamoDB.
C
Shapefile C Library - Provides the ability to write simple C programs for reading, writing and updating (to a limited extent) .shp and .dbf files.
Datamaps - This is a tool for indexing large lists of geographic points or lines and dynamically generating map tiles from the index for display.
Heatmap.js - A heatmap implementation for Javascript.
Thermo.js - Another heatmap implementation for Javascript.
Heatcanvas.js - Yet another heatmap implementation for Javascript.
GeoExt - Open Source and enables building desktop-like GIS applications through the web. It is a JavaScript framework that combines the GIS functionality of OpenLayers with the user interface of the ExtJS library provided by Sencha.
iTowns - A Three.js-based framework written in Javascript/WebGL for visualizing 3D