app.py

from flask import Flask, render_template, request
import requests
import hashlib

app = Flask(__name__)

def request_api_data(query_char):
    url = 'https://api.pwnedpasswords.com/range/' + query_char
    res = requests.get(url)
    if res.status_code != 200:
        raise RuntimeError(f'Error fetching: {res.status_code}, check the API and try again')
    return res

def get_password_leaks_count(hashes, hash_to_check):
    hashes = (line.split(':') for line in hashes.text.splitlines())
    for h, count in hashes:
        if h == hash_to_check:
            return count
    return 0

def pwned_api_check(password):
    sha1password = hashlib.sha1(password.encode('utf-8')).hexdigest().upper()
    first5_char, tail = sha1password[:5], sha1password[5:]
    response = request_api_data(first5_char)
    return get_password_leaks_count(response, tail)

@app.route('/', methods=['GET', 'POST'])
def check_password():
    result = None

    if request.method == 'POST':
        password = request.form['password']
        count = pwned_api_check(password)
        if count:
            result = f'{password} was found {count} times... you should probably change your password!'
        else:
            result = f'{password} was NOT found. Carry on!'

    return render_template('index.html', result=result)

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