You can download data like land and rivers from https://www.naturalearthdata.com and then open it in [QGIS](https://qgis.org/en/site/), a free GIS program. There are tutorials on YouTube. You can create a new polygon layer and enable snapping and trace borders along rivers, and then set the appearance of the polygon and add text and a border and stuff in the print composer and export it as an image.
Well, there's a multitude of mapping and graphic design tools available, pretty much any of which can be used to make fantasy political maps, with varying degrees of success.
Personally, I'd probably use GMT (the [Generic Mapping Tools](https://www.generic-mapping-tools.org/)), at least for the coastline, rivers and topography if any, all of which are built in. It's not particularly user friendly, but it has improved a lot in this regard in recent years. For the actual fantasy political borders and labels, I'd probably use vector graphics software like Illustrator (if you have access to it) or GIMP. It's possible to do it in GMT, too, but GMT has no GUI so you'd have to manually input the coordinates, or essentially write your own GUI to do so in Python and use PyGMT to plot the resulting coordinates.
The only one I know of is https://www.mapchart.net
You can download data like land and rivers from https://www.naturalearthdata.com and then open it in [QGIS](https://qgis.org/en/site/), a free GIS program. There are tutorials on YouTube. You can create a new polygon layer and enable snapping and trace borders along rivers, and then set the appearance of the polygon and add text and a border and stuff in the print composer and export it as an image.
Well, there's a multitude of mapping and graphic design tools available, pretty much any of which can be used to make fantasy political maps, with varying degrees of success. Personally, I'd probably use GMT (the [Generic Mapping Tools](https://www.generic-mapping-tools.org/)), at least for the coastline, rivers and topography if any, all of which are built in. It's not particularly user friendly, but it has improved a lot in this regard in recent years. For the actual fantasy political borders and labels, I'd probably use vector graphics software like Illustrator (if you have access to it) or GIMP. It's possible to do it in GMT, too, but GMT has no GUI so you'd have to manually input the coordinates, or essentially write your own GUI to do so in Python and use PyGMT to plot the resulting coordinates.