Definitely looks pretty cool! Never heard of it before, I got this from their "about us" (although I still feel I don't fully know who they are or what their goals are):
About Mapcarta
Explore the globe with Mapcarta—the open map that unites the world through the collective knowledge of OpenStreetMap, Wikipedia, Wikidata, and other open projects.
Contributions
Help us improve our map—edit our open data sources directly. Your updates typically appear on Mapcarta within a few weeks.
Our Mission
At Mapcarta, our goal is to provide intuitive maps and insightful guides crafted from shared open knowledge—to foster curiosity, connection, and understanding.
Open, Independent, Sustainable
Mapcarta is built on open data and Creative Commons resources. Your contributions to projects like OpenStreetMap and Wikidata directly improve Mapcarta and support open, sustainable mapping for all.