Libretranslate but with post and response changed to work with MORT.
Just replace the app.py file in the directory where libretranslate is installed.
e.g. ...\AppData\Local\Programs\Python\Python310\Lib\site-packages\libretranslate
Change the MORT translator to custom api.
And specify the URL from advanced options.
In Libretranslate the default url is http://127.0.0.1:5000
Run Libretranslate and done.