Diapason Simple is a free, basic tuning fork app available on Android platforms. Developed by Prokaryo, it is a simple and easy-to-use application that plays a recorded sound of a real A-440 tuning fork.

The app interface is straightforward, with a large and prominently displayed image of a tuning fork. Users can play the sound at any time by tapping on the image. There are no additional features or settings, making it a useful tool for musicians or anyone who needs to tune instruments or other devices to the A-440 frequency.

Overall, Diapason Simple is a reliable and straightforward app that serves its purpose well. However, for those looking for additional features, an enhanced version called "Diapason" is available for download.