Derus.hu napszakok is a free Chrome add-on developed by Ákos T. It falls under the category of Browsers and specifically the subcategory of Add-ons & Tools.

This add-on provides users with the ability to easily determine the duration of each time period of the day on derus.hu. With just a few clicks, users can find out when a particular time period starts and ends.

Overall, Derus.hu napszakok is a useful tool for those who want to keep track of the duration of different time periods throughout the day. Its simplicity and convenience make it a valuable add-on for Chrome users.