the result i want is another json

Thank you for slightly clarifying your objective. However, as we have also made clear, we still do not know anything about the conversion you want to perform, beyond the fact that it is a conversion between two JSON formats. This is a Notepad++ forum, not a forum for any random programming question you might have; that would be StackOverflow. This sounds like a question you should ask there, or answer for yourself by consulting a search engine.

If you expect this forum to be at all useful to you, you need to explain clearly what you are trying to do, rather than giving a vague description of your goal and expecting us to infer the rest.

As mkupper said, JsonTools can help you view and navigate JSON files, but it doesn’t have any specific tools to help with “blender fbx bones format”.

I suggest you use your favorite search engine to learn more about that format; I was not able to find any obviously useful information in the very cursory Google search I did before writing this response.

Notepad++ has a JSON Tools plugin but your description of what you want to do is so vague that I have no idea if JSON Tools will help or hinder what you are trying to do.

In the subject line you say you want to convert a JSON file into a different JSON file. In the body of the message this is less clear on if you want the result to be JSON or something else.

Notepad++ is not a universal data transformation tool though can do many useful things to help you to transform from one text or character based file into another.