Koop

Koop is a JavaScript toolkit for making requests to spatial APIs. It exposes a Node.js web server that facilitates on-the-fly transformations of geospatial data from one format to another and delivers it to clients by HTTP. Koop allows you to keep your data in its native format while making it accessible in any format required. Out-of-the-box, Koop can translate your data into the GeoServices specification supported by ArcGIS products. Its plugin architecture supports output in other formats including vector-tile, WMS, and plain old GeoJSON. Koop's plugin-architecture facilitates custom deployments specific to your needs. "Provider" plugins to connect to novel data formats and translate to a common format (GeoJSON), while "output" plugins then transform that GeoJSON to other specifications. See a list of plugins already authored and maintained here. If you have a novel data source or require an as-yet unsupported output format, new plugins can be easily developed and integrated.