Open Location Code is a library to generate short codes, called "plus codes", that can be used as digital addresses where street addresses don't exist.

GeoGebra apps (mirror)

Real Time communication library using Animated Gifs as a transport™

Node-based data application for visualization and generative design

Hadoop library for large-scale data processing, now an Apache Incubator project

Create custom vector tiles from OpenStreetMap and other data sources with Postgis and Java.

Basemap PMTiles generation and cartographic styles for OpenStreetMap data and more

GeoWave provides geospatial and temporal indexing on top of Accumulo, HBase, BigTable, Cassandra, Kudu, Redis, RocksDB, and DynamoDB.

Next generation vector tiles format

Bin-based rendering...for the win!

History Hackday project: visualizing the time and place of events recorded in Wikipedia

Java class for creating tweetable mazes (using unicode box characters).