Question

Is it possible to integrate Java, Python, or Objective C directly with the Firefox browser? In particular to do “real”, native tasks such as writing files or connecting to a local database, or better yet, directly calling systems level code ?

Notably, there is a post on native code execution, somewhat slanted towards windows, elsewhere on StackOverflow: Firefox extension: native code execution?

Answer 1

In particular to do “real”, native tasks such as writing files or
connecting to a local database, or better yet, directly calling
systems level code ?

You don’t need an extra language for that, Firefox extensions can do it already:

• Writing files
• Connecting to a local SQLite database
• Calling system libraries directly

I would recommend against attempting to write the extension in anything other than JavaScript: while there are several possibilities they create a lot more trouble than they are worth. If anything, you could create a native library and call it from your JavaScript code via js-ctypes (see link above).