AtCoder Calendar is a convenient Chrome extension developed by penicillin0 that allows users to effortlessly add AtCoder contests to their Google Calendar. This free add-on falls under the category of Browsers and specifically the subcategory of Add-ons & Tools.

With AtCoder Calendar, users can generate a schedule link for Google Calendar directly on the AtCoder contest site. This makes it incredibly easy to add upcoming contests to their calendar without any hassle. By simply clicking on the generated link, users can seamlessly integrate the contest schedule into their Google Calendar, ensuring they never miss an important event.

It's important to note that AtCoder Calendar is an unofficial extension, so users should exercise caution and use it at their own risk. However, it provides a simple and efficient solution for AtCoder enthusiasts who want to stay up to date with contest schedules.