Morse Code Trainer Learn CW is a free educational application developed by Claus Niesen for Android users. The app is designed to help users learn Morse code by sound rather than by remembering dots and dashes. The app plays characters, words, and phrases in Morse code, providing a brief moment for users to recognize it before speaking out the answer. The app also includes a user setting to repeat character/word/phrases multiple times before moving on to the next one.

Moreover, the app allows users to customize their own word list, set speed, farnsworth spacing, pitch, and more. It also comes with pre-installed word lists, such as the alphabet, numbers, symbols, memory words, and a combination of all three. The app requires write access to the user's device's USB storage to work. The directory "Claus' Morse Trainer" is created for the word lists, which can be safely deleted after uninstalling the app.

Morse Code Trainer Learn CW is created out of love for coding and amateur radio, and it's open-source. The app doesn't collect any data, so there is no need for a privacy policy. Users can report any issues and errors via GitHub, and code contributions to improve the Morse code trainer are welcome as well.