OK Note - Notepad Calendar is a free Android application developed by wscellbox. It falls under the category of Utilities & Tools, and it offers a range of features to help manage your notes, to-dos, and schedules.

The app allows you to write text notes, manage to-dos and shopping lists, enter schedules in the calendar, and receive notifications. You can also write a diary on the calendar, and classify your notes by folder and color. The app supports various layouts, such as list, grid, calendar, and calendar+list, to help you organize your notes effectively.

Additionally, OK Note - Notepad Calendar supports data backup and recovery, search function, and the ability to restore deleted notes. You can also create widgets on your home screen and use the lock function to secure your notes.