Your website sometime has many category and subcategory, it's okey if Category has 2 sub category, but it's will be bad if category has more than 3 children, this simple plugin will help you shorten all of them to a nicer permalink.
A permalink with a depth of more than 3 levels doesn't look too user friendly. Additionally, Google may not worry much about URL depths, though it may impact searches on other engines like Bing or Yahoo. This plugin help you shortening deep subcategory's link !
Eg:
//domain.com/category-parent/subcategory/subofsubcategory/last-subcategory.html
Now it's will be:
//domain.com/nameof-the-category.html
You can choose the end of the Url, can be html or htm or something like ".jam" is okey !
This plugin work with Yoast SEO also, no worry about anythings !
After active this plugin, you have to go to Admin > Setting > Permalinks to set-up suffix for Category link, or plugin will do nothing, suffix can be anything, eg: ".html" or ".asp" or even ".amazon"
Now the best way to setting main custom structure is "/%postname%" without the '/' at the ending of URL, so the category's link after shorten will have no slash at the end.
Just unzip plugin and move all of theme to plugins folder inside Wordpress directory, then go to Admin > Plugins to active it, ALL Done !