Downloading InspectorXL 1.0 for Mac from the developer's website was possible when we last checked. We cannot confirm if there is a free download of this app available. We recommend checking the downloaded files with any free antivirus. The program lies within Audio & Video Tools, more precisely General.
From the developer:
InspectorXL (a.k.a. IXL) was designed to address the most common analysis tasks with professionalism, style, and finesse. Available as a series of "modules," InspectorXL includes six (6) individual, thoughtfully designed plug-ins for: FFT, spectragram and Third Octave spectral analysis, custom and standard level metering, phase and correlation, balance, stereo image, and statistical clipping and over analysis.