These are some examples of programs I made using the Steinberg VST SDK and a couple of other tools (programmed in C++ and Delphi).
Some of the programs are available in the download section (32bit plugins; with 64bit OS and 64bit DAWs you'll have to use it bridged).
FA1 (VST FFT-Frequency-Analyzer)
PA1 (VST FFT-PhaseAnalyzer)
MSTools (VST tools for MS-Processing)