How to add borders between cells in heatmap

Scenario:

You have a heatmap and would like to add borders between cells for better readability. The available advanced properties don't have any property that suggests changing that. How to add the border?

Solution:

The property for the heatmap borders is not included in the properties available in the advanced property window. However, you can add them manually by pressing the Add button in the advanced formatting properties view and type:

plotOptions.heatmap.borderWidth - pass a numeric value, like 1 to make borders appear.

plotOptions.heatmap.borderColor - pass a color, can be web color name like black or red or can be a hexadecimal value.