In the age of smart phones and tablets, it is not possible to carry around a classic, vintage analog tuner. Most mobile devices don't have the accuracy, and even if they do, the battery life may not be compatible with the device.

Fortunately, there is an app for that. The app is called Keuwl, and it is designed for musicians. It is an accurate guitar tuner, but it also detects the pitch of other instruments. The user interface is very intuitive and the accuracy is definitely better than most mobile devices.

The app is free, so there is no need to worry about any kind of trial version. You can also download the full version without any limits. The only requirement is that you need to have a microphone to use the app.