The RT Topology Library exposes an API to create and manage standard (ISO 13249 aka SQL/MM) topologies using user-provided data stores and released under the GNU GPL license (version 2 or later). The code is derived from PostGIS liblwgeom library enhanced to provide thread-safety, have less dependencies and be independent from PostGIS release cycles. WWW: https://git.osgeo.org/gitea/rttopo/librttopo