[JTxt]

Seems like it. Did you try this?:

https://www.google.com/search?q=onenote+file+parser https://github.com/dropbox/onenote-parser

[fredsanford]

I haven't been able to get this one to work with any of my onenote files. FWIW.

I have found no other parser with source.

[fluentcar]

While I hadn't tried GP's dropbox/onenote-parser, it's what I had suspected, considering it looks abandoned with no activity in almost an year.