jts

JTS, the Java Topology Suite, is an open-source Java library that provides a comprehensive geometry model and algorithms for working with planar spatial data. It implements the core geometry types and operations used in many geographic information system (GIS) applications, including points, lines, polygons, and collections, along with precision handling and factory utilities for creating geometry objects.

The library offers a broad set of capabilities. It implements spatial predicates such as intersects, contains, within, crosses, and touches, as well as topological and overlay operations like union, difference, and intersection. It also provides relation and topology tools for detecting and describing how geometries relate to each other, and it includes mechanisms to build and manipulate complex geometries while preserving topology. JTS includes spatial indexing structures such as STRtree and Quadtree to accelerate queries and supports input/output in well-known formats such as WKT (Well-Known Text) and WKB (Well-Known Binary).

JTS serves as the geometry kernel for many Java-based GIS projects and has influenced or formed the basis of related implementations, including GEOS (the C++ port used by PostGIS) and JSTS (a JavaScript port). It underpins a wide range of GIS software and web mapping tools, enabling robust geometric computation and spatial analysis. The project emphasizes careful handling of numerical precision and edge cases, aiming to provide a stable, well-documented API for integration into larger GIS workflows and software stacks.