Try it out! Change the subject of any text from male to female and vice versa.
This Extension generally depends upon decent grammar (though it recognizes some common spelling mistakes).
Furthermore it does not change names, only pronouns.
I suggest to try out the formular above to see just how well the algorithm works.
This Extension is open source under the GPL3 licence.
You can access the source files by simply opening the XPI or CRX file with 7zip or winrar.