anyone know how to debug chrome extention independently (not using google chrome)
 

I am recently doing some experiments with Grammarly google chrome extension. you can bypass the premium popup because this popup is not server-side. at the first time login, it receives some JSON which includes your subscription plan, and use it to restrict your membership.. but the main problem is I can't find the exact main root when it first store the JSON object as a javascript object in the window object and read it from there... so I need a good debugger.

Why do you have to be not in google chrome? What happens if you toggle on debug mode -- https://developer.chrome.com/docs/extensions/mv3/tut_debugging/? If it detects dev tools there are workarounds (for anti-anti-debugging). What about Chrome's extension source viewer? (link: https://chrome.google.com/webstore/detail/chrome-extension-source-v/jifpbeccnghkjeaalbbjmodiffmgedin)

I understand that to use it you:

• Click on the yellow CRX button, and choose "Download"
• Extract the zip file.
• Read the source code, and change it.
• Visit chrome://extensions/
•  Enable Developer mode, by activating the switch in the upper-right corner.
•  Click on the "Load unpacked extension" button.
•  Select the folder of your extension (there should be a manifest.json).
• Confirm, and load the modded one. That should let you get by anti-anti-debug if present.

Assuming you don't want a standalone debugger [I don't think there is one for debugging chrome extensions without using chrome] but a debugger that leverage chrome to debug the JavaScript code.

there is webstorm from jetbrains which has a very good debugger that leverage any Chromium-based browsers to debug javascript
https://www.jetbrains.com/help/webstorm/debugging-javascript-in-chrome.html
https://blog.jetbrains.com/webstorm/2018/01/debugging-javascript-with-webstorm-2017-3/

there is also Chrome Debugging for VS Code
https://code.visualstudio.com/blogs/2016/02/23/introducing-chrome-debugger-for-vs-code

Also you can arm your chrome devtools with extensions to enhance your experience and improve chrome developer tools