Since it is a free software , you can contribute to make it better. New contributors are always welcome, whether you write code, create resources, report bugs, or suggest features.
Frontend- The frontend of J.A.R.V.I.S is written using html and css. If you want to improve the frontend go to the templates folder and make the changes you want but remember to include a screenshot when you create a pull request
Backend- The backend of J.A.R.V.I.S is written using python3. If you want to improve the backend go to the backend folder and make the changes you want