GeoServer Alternatives

MapServer is an free and open-source platform for publishing spatial data and interactive mapping applications to the web. Originally developed in the mid-1990’s at the University of Minnesota, MapServer is openly developed and released under an MIT-style license, and runs cross-platform on macOS, Linux and Windows. MapServer is not a full-featured GIS system, nor does it aspire to be. 

Mapbox Studio is a suite of applications for designing custom map styles and managing your location data with Mapbox. You can use Mapbox Studio to build and design a map to your exact specifications by uploading and editing your own data, utilizing Mapbox-provided tilesets, adding custom fonts and icons, or refining the built-in core styles.

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Map3 is a decentralized map network, governed and distributed over a p2p network.

Yandex.Maps provides detail maps of the whole world. It's the most popular mapping service in Russia, developed by the internet giant Yandex which. It serves over 20 million users worldwide every month, which use the application to find locations and get travel directions for driving, walking and commuting with public transport.