AudioMass

AudioMass lets you record, or use your existing audio tracks, and modify them by trimming, cutting, pasting or applying a plethora of effects, from compression and paragraphic equalizers to reverb, delay and distortion fx. AudioMass also supports more than 20 hotkeys combinations and a dynamic responsive interface to ensure ease of use and that your producivity remains high. it is written solely in plain old-school javascript, weights approximately 65kb and has no backend or framework dependencies.

It also has very good browser and device support.

FEATURES Loading Audio, navigating the waveform, zoom and pan Visualization of frequency levels Peak and distortion signaling Cutting/Pasting/Trimming parts of the audio Inverting and Reversing Audio Exporting to mp3 Modifying volume levels Fade In/Out Compressor Normalization Reverb Delay Distortion Pitch Shift Keeps track of states so you can undo mistakes Offline support