source: hongkiat.com

1. Audacity
Audacity® is free, open source software for recording and editing sounds. It is available for Mac OS X, Microsoft Windows, GNU/Linux, & other operating systems.

2. Power Sound Editor
Power Sound Editor Free is a visual audio editing and recording software solution, which supports many advanced and powerful operations with audio data.

3. MP3 Direct Cut
mp3DirectCut is a fast and extensive audio editor and recorder for compressed mp3. You can directly cut, copy, paste or change the volume with no need to decompress your files for audio editing.

4. Music Editor Free
Sound editing functions include cut, copy, paste, delete, insert, silence, trim and more. Audio effects include, amplify, normalize, equalizer, envelope, reverb, echo, reverse, sample rate conversion and much more. Includes its own CD ripper/Burner.

5. Wavosaur
Wavosaur has all the features to edit audio (cut, copy, paste, etc.) produce music loops, analyze, record, batch convert. Wavosaur supports VST plugins, ASIO driver, multichannel wav files, real time effect processing.

6. Traverso DAW
Is a GPL licensed, cross platform multitrack audio recording and editing suite, with an innovative and easy to master User Interface. It's suited for both the professional and home user, who needs a robust and solid DAW.

7. Ardour
Unlimited audio tracks and buses, Non-destructive, non-linear editing with unlimited undo, Anything-to-anywhere signal routing.

8. Rosegarden
Rosegarden is a well-rounded audio and MIDI sequencer, score editor, and general-purpose music composition and editing environment.

9. Hydrogen
Hydrogen is an advanced drum machine for GNU/Linux. It's main goal is to bring professional yet simple and intuitive pattern-based drum programming.

10. WavePad Sound Editor
This sound editing software is a full featured professional audio editor for Windows or Mac. It lets you make and edit music, voice and other audio recordings. When editing audio files you can cut, copy and paste parts of recordings and, if required, add effects like echo, amplification and noise reduction.

11. Sound Engine
SoundEngine is the best tool for personal use, because it enables you to easily edit a wave data while it has many functions required for a mastering process.

12. Expstudio Audio Editor
Expstudio Audio Editor is shipped in two different editions. The Free version contains all the functionality of the professional version but only can save audio files as Uncompressed WAV PCM (*.wav) and mp2 (*.mp2).

13. DJ Audio Editor
DJ Audio Editor is easy-to-use and well-organized audio application which allows you to perform various operations with audio data. You can create and edit audio files professionally, by having ability to apply dozens of amazing effects to audio files such as Amplify, Flanger, Chorus, Reverb, Invert and Reverse.

14. Eisenkraut
Eisenkraut is a cross-platform audio file editor. It requires Java 1.4+ and SuperCollider 3. It supports multi-channel and multi-mono files and floating-point encoding. An OSC scripting interface and experimental sonagramme functionality are provided.

15. FREE WAVE MP3 Editor
It's got many advanced, high-tech, features that you've (at least I've) never seen before. We got bored with developing the same old thing so went far off the beat'n path (while still keeping it real;-) with development of this editor/ recorder.

16. Kangas Sound Editor
The home of the Kangas Sound Editor and the Kangas Sound Editor QI. Download the Kangas Sound Editor or Kangas Sound Editor QI for free. Although it comes from Oz, you don't need to use it upside down!

17. Ecawave
Ecawave is a simple graphical audio file editor. The user-interface is based on Qt libraries, while almost all audio functionality is taken directly from Ecasound libraries. As ecawave is designed for editing large audio files, all processing is done direct-to-disk

18. Audiobook Cutter
Split your MP3 audio books and podcasts in a fast and user friendly way. The split files can easily be used on mobile MP3 players because of their small-size. Their duration allows smooth navigation through the book. The split points are determined automatically based on silence detection.

19. Jokosher


20. LMMS


21. Mp3Splt


22. Qtractor


23. ReZound


24. Sweep


25. Wavesurfer