GeoServer is an open-source server written in Java that allows users to share, process and edit geospatial data. Designed for interoperability, GeoServer publishes data from any major spatial data source using open standards.
GeoServer implements industry standard OGC protocols such as Web Feature Service (WFS), Web Map Service (WMS), and Web Coverage Service (WCS). It produces high quality rendering of maps and can handle hundreds to thousands of map layers easily.

Additional formats and publication options are available as extensions including Web Processing Service (WPS), and Web Map Tile Service (WMTS). Works very well with postGIS and handles raster data with ease. GeoSever is capable of handling even the most storage hungry datasets.
Geoserver I
1 CPU
2 GB RAM
50 GB SSD Storage
Geoserver ll
2 CPUs
4 GB RAM
80 GB SSD Storage
Geoserver lll
4 CPUs
8 GB RAM
160 GB SSD Storage