Others can make more informed recommendations; to the best of my knowledge it's going to depend on your keyboard and what firmware it runs. (There are some os-level heatmappers you can use, too.) When I used a Voyager I used the Heatmap feature in ZSA's keymapp app. When I was using a corne I used Via/Vial to do it. I finally found my way to the glove and used the data from those.
Others can make more informed recommendations; to the best of my knowledge it's going to depend on your keyboard and what firmware it runs. (There are some os-level heatmappers you can use, too.) When I used a Voyager I used the Heatmap feature in ZSA's keymapp app. When I was using a corne I used Via/Vial to do it. I finally found my way to the glove and used the data from those.