Important
I respect the Developer of webNBT and in no way do I want to create something better, I have been using webNBT for a while, and love it really, I simply wanted to make something easier to access when offline.
That being said, I don't think there is a single flaw with webNBT and I strongly think it is the most convenient NBT Editor there is
Below are the 2 sections containing info about both the app, and the website this was forked from. (webNBT's section will not be modified and is as it was when I forked the repo.)
An HTML5 NBT-editor based on emscripten (Created by iRath96)
Allows you to edit NBT-files saved by Minecraft directly in your browser - no need to download anything!
Check out the live-demo.
A fork of webNBT embedded in an Electron for offline convenience.
Currently only Embeds the webNBT in an Electron App, more changes will come soon. As I am currently typing this, I am tired, I will probably work on it more in the morning.