Beatifiers

JSON

1. JSON echo '{"test":"a"}' | python3 -m json.tool или python3 -m json.tool in_json.txt out_json.txt

JS

pip install jsbeautifier
js-beautify -h
js-beautify -o out.js in.js

или код:
import jsbeautifier
data = 'import blabla;'
data = jsbeautifier.beautify(data)

XML/HTML

from bs4 import BeautifulSoup

bs = BeautifulSoup(data, 'xml')  # 'html.parser'
data = bs.prettify()