LocationTech

The JTS Topology Suite is a Java library for creating and manipulating vector geometry.

GeoWave provides geospatial and temporal indexing on top of Accumulo, HBase, BigTable, Cassandra, and DynamoDB

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

GeoTrellis is a geographic data processing engine for high performance applications.

uDig parent project containing all core components. More plugins can be found in community repos: http://github.com/uDig-Community

Geospatial Raster support for Spark DataFrames

LocationTech Spatial4j: A Geospatial Library for Java

GeoGig project

Java port of the Proj.4 library for coordinate reprojection

Geoff project at LocationTech

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

Geobench project