ToDo

ToDo is a lightweight piece of software that enables you to take note or add reminders without having to stop what you are doing or close any applications you are using.

Comes with a clean and uncluttered interface

The program does not require installation, but rather you can unpack it in any desired location on your local drives. Upon launch, you come face to face with a minimalistic, yet appropriate interface that is designed like a notebook file.
The main window is split into several tabs that are representative of the type of data they display. Therefore, you can preview your notes based on the time they are taken, time due as well as a short description of the activity that you need to complete. Alternatively, you can deselect the data and time and only add a note about data that you want to remember.

Alerts you when an event is almost due

The highlight of the application stems from the fact that you can configure it so that it alerts you before the timer set for the tasks is finished. In fact, you can set the app to pop up the main window when the event is almost due, with or without seconds.
In the eventuality that you do not like the default sound used for the alert, then you should bear in mind that you can select any audio sample you store in a WAV file. Another option would be to record your own alert using the speech-to-text capabilities of the program.
While you can delete all expired entries with just one click, it is worth mentioning that you can also set the app to remove them after a certain interval automatically.

A useful and convenient tool for taking notes

All in all, if you are looking for a straightforward solution that provides you with a quick way to take notes but without having to stop everything you are doing for this purpose, then perhaps ToDo might come in handy.