A program for phonetic speech analysis. Allows you to analyze digital sound files in various ways, including spectral analysis, pitch analysis and formant analysis.

Access: Download for Linux, macOS and Windows (Free)

Link: http://www.fon.hum.uva.nl/praat/

An easy-to-use website that lets you create syntax trees like this one:

Access: Online (Free)

Link: http://mshang.ca/syntree/