A free program for Android, by SoundBase Audio LLC.

The free version of WaveEditor is useful and is compatible with most devices, including mobile devices and tablets. However, if you want to get the best out of this app, you need to upgrade to the latest version. This can be done within the app via In App Billing. The upgraded version of WaveEditor contains many improvements and is more useful. 

With the latest version of WaveEditor, you can do the following:

Create and edit audio files. Record and mix audio. Play audio. Convert audio to MP3. Play and edit MP3s. Edit MP3s and convert them to WAV. Edit WAVs.