Guitar Fretboard Trainer is an Android app developed by Robert Lyon that helps you practice memorizing the fingerboard of a guitar. The app is designed to help open up your guitar playing by allowing you to pick and choose notes of a specific key without relying on scale patterns or chord shapes. The program is free to download and falls under the games and music categories.

The app's main feature is a timer that challenges you to hit as many notes as possible within two minutes. This feature adds a level of excitement and competitiveness to the learning process, making it more engaging and enjoyable. The app is perfect for those who want to improve their guitar playing skills and memory of the fingerboard.