Using Flask's jsonify displays é as é

You're viewing the representation of the dumped data. Since you've disabled JSON_AS_ASCII, you get two UTF-8 bytes rather than an ASCII-compatible Unicode escape. JSON is still UTF-8, regardless of which representation you choose, but it is typically safer to stick with the default.

Whatever you're using to view the data is misinterpreting the bytes as Latin-1, not UTF-8. Tell whatever you're viewing the data with that it's UTF-8, and it will look correct. Load the data from JSON and you will see that it is still correct.

from flask import Flask, jsonify, jsonapp = Flask('example')app.config['JSON_AS_ASCII'] = True  # defaultwith app.app_context():    print(jsonify('é').data)  # b'"\\u00e9"\n', Unicode escapeapp.config['JSON_AS_ASCII'] = Falsewith app.app_context():    print(jsonify('é').data)  # b'"\xc3\xa9"\n', UTF-8 bytes# you're viewing the bytes as Latin-1print(b'\xc3\xa9'.decode('latin1'))  # é# but it's UTF-8print(b'\xc3\xa9'.decode('utf8'))  # é# JSON is always UTF-8print(json.loads(b'"\\u00e9"\n')  # éprint(json.loads(b'"\xc3\xa9"\n')  # é