GEOS (Geometry Engine, Open Source) is a LGPL licensed C++ port of the JTS Topology Suite, used by many free software packages (PostGIS, Quantum GIS, MapServer to name a few) for low-level topological operations.
Initially sponsored by Refractions Research and
under the technical advice of
Martin Davis (JTS designer),
GEOS was the engine that would turn
into a fully compliant OGC spatial database.
Martin wrote his version of the story up to that point here.
In late 2003 I got a consulting contract from Refractions to work (remotely) on setting GEOS straight to a 1.0 level, after a period of struggling with memory leaks making an official release impossible. That's when I met (virtually) Paul Ramsey.
Since then I've continued to work
on the codebase with different committment levels.
Notable improvements I worked on, beside the overall maintainance, include: