Hi, I updated my Python script to use it for some sites that accepts just letters, and numbers. You can use it while sing up... It is written by Mustafa Sarialp and its licence Public Domain.

create_password2.py

#!/usr/bin/env python3
# ====================================================================================================================================================
# Name        : create_password.py
# Author      : Mustafa Sarialp
# Version     : 2.0.2
# Copyright   : Public Domain
# Description : Updated version of my Python 3 script "create_password" which you can create a password without special charecters for using with some 
# web sites which don't support special characters like "#, &, %, !, ...". This script creates  simpler passwords than version 1.0.
# ====================================================================================================================================================

import random
def create_password():
    password = []
    new_password = ''
    letters = 'abcdefghijklmnopqrstuvwxyz'
    for i in range(12):
        letter = random.choice(letters)
        number = random.randrange(0, 10, 1)
        if i % 3 == 0:
            if i / 3 > 2:
                password.append(letter.capitalize())
            else:
                password.append(letter)
        elif i % 2 == 0:
            password.append(str(number))
        else:
            if i % 4 == 0:
                password.append(str(num))
            else:
                if i / 4 > 1:
                    password.append(letter.capitalize())
                else:
                    password.append(letter)
    random.shuffle(password)
    new_password += random.choice(letters)
    for j in range(12):
        new_password += password.pop()
    return new_password
  
if __name__ == '__main__':
    key = ''
    while key != 'q':
        my_passwd = create_password()
        print("You can use: ", my_passwd, " as creating normal password.")
        key = input("To create new one press 'c' or to quit press 'q': ")