CartoCSS

CartoCSS (Carto) is a language and compiler for designing maps, targeting the Mapnik renderer. It compiles CSS-like style rules into Mapnik XML or JSON. Current stable version is 1.2.0 (released with updated dependencies and support for new Mapnik API versions). Maintained by Mapbox, with irregular releases. Key differentiators: CSS-like syntax familiar to web developers, variable support, map data filtering, and compatibility with tools like TileMill, Kosmtik, and Mapbox Studio Classic.