Java port of the Proj.4 library for coordinate reprojection

LocationTech SFCurve is a Scala library for the creation, transformation, and querying of space-filling curves

GeoGig project

GeoMesa is a suite of tools for working with big geo-spatial data in a distributed fashion.

LocationTech Spatial4j: A Geospatial Library for Java

Geospatial Raster support for Spark DataFrames