What open source and free wireframing tools are there? [duplicate]

This question already has an answer here:

I am writing a tutorial on how to do wireframing: https://github.com/dwyl/learn-wireframing/issues/1 and I would like to be able to recommend an online, free and open source wireframing tool to others. However I am struggling to find one that is open source, free and online.

I have come across this SO question: https://stackoverflow.com/questions/3432665/open-source-or-free-wireframe-tools and this article https://www.briefside.com/free-open-source-wireframe-tools/

However neither of them detail currently free and open source tools aside from Pencil which is desktop only and was last updated in 2017.