This calculator uses information from here.
Run the main.py with py main3.py
if you're using Python 3 or python main2.py
if you're using Python 2. You'll be prompted to enter your gross annual income. It'll quickly spit out how much you'll pay in 2021 federal income taxes and how much you'll have left.
See for-bash-profile.sh
for information on creating a bash alias for this tool.