Create a multi site Flask application using Blueprints. This app will match hostname to serve a distinct application.

app.py

# set up /etc/hosts
# 127.0.0.1 site1.loc site2.loc

from flask import (
    Flask
)

import site1, site2 

app = Flask(__name__)
app.url_map.host_matching = True

app.register_blueprint(site1.app)
app.register_blueprint(site2.app)

if __name__ == '__main__':
    app.run(debug=True, port=5000)

site1.py

from functools import partial
from flask import (
    Blueprint, jsonify
)

app = Blueprint('site1', __name__)
route = partial(app.route, host="site1.loc:5000")

@route("/")
def home():
    return jsonify(
        hello='site1'
    )

site2.py

from functools import partial
from flask import (
    Blueprint, jsonify
)

app = Blueprint('site2', __name__)
route = partial(app.route, host="site2.loc:5000")

@route("/")
def home():
    return jsonify(
        hello='site2'
    )