What is the recommended platform for making HTML/JS applications?
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I might be missing the point as I'm not sure about the terminology, so feel free to edit the title of this question.

Basically, I would like to know if there are any open source tools that work like programs in order to run HTML and Javascript code. Web browsers are able to do that, yes, but that's different. I'm wondering if there's a dedicated application for the purpose of running programs written in JS (+HTML/CSS) that can be redistributable freely with any such program.

I've been writing a Javascript/HTML/CSS GUI for at least a few weeks - it has been fun to do so far, but I've noticed that the project may grow into something bigger and it just can't simply depend on an internet browser (also, I'm not sure about the security of running a JS app which doesn't connect to the internet in an internet-ready browser).

Thank you.