Sound Level Meter - You can measure the environmental noise in decibels.

Friture - Friture is a program designed to analyze audio input in real-time.

Digital Level Meter - Display sound level

xoscope - Xoscope uses the input of your Sound Card, EsounD and/or a ProbeScope/osziFOX and Bitscope-Hardware.

AudioTool - Whether you want to make music for the club, or you're aiming to put a few tracks to a film, Audiotool is a website geared towards putting the mixes at your fingertips. Read more about AudioTool.

Signalizer - Signalizer is an all-in-one signal visualizing package for VST, VST3 and AudioUnits