Fantasy Map Generator (FMG) is a free online tool which produces procedurally generated and highly customizable fantasy maps. You can just use auto-generated maps or create your own world from scratch.
Exploration - click on the New map! button to get a random map. Open the Style settings (press Tab) and select a desired layers preset. Zoom in and explore the generated world
Tuning - go to Options, change the default settings like map template and states number and generate a new map to better fit your needs More Info »
Customization - open the Tools tab, select one of the available editors and change the map in any desired way
Controlled generation - open the Tools tab, then click on Heightmap and select an Erase mode. Click on Template editor and create your own heightmap template. Apply the template to see the result. Don't forget to share good templates with the community!
Conversion - if you already have a map image and want to re-create it in a generator, open the Image converter (the button next to Template editor), load the image and fine-tune the conversion into a heightmap. Then edit the map using the Tools provided
Drawing - use the Paint brushes to draw a map from scratch. It may takes a lot of time, so I would recommend you to follow the Controlled generation approach to get a basic landmass and then use Paint brushes for a fine-tuning