Years ago there was some type of "add-on" a programmer had made for MFP to give net carbs, but I used the suggestion to re-arrange the columns, and to write net in Notes if needed. The free MFP allows any five macros/nutrients, so I arrange the columns with TC and fiber, 1 and 2. Visually easy to subtract in my head during the day.

Not that I track often, but one reason it is hard to switch after years on MFP is the recipes and meals I have saved. There are complaints about user entries on MFP but so many users also means popular Low Carb recipes are already entered and saved. Kristie Sullivan is a popular Keto cookbook author, if you search well using her name, many recipes from her two cookbooks are there.