OTP generator application with GUI using Python and Tkinter

In this article, we are going to create a Graphical User Interface based OTP generator application in Python. We will see how to create a GUI app using Tkinter and how to add functionality to its front end. We will create an app that will generate an application that will generate a One Time Password (OTP) of 4 digits and display it on the application whenever the "Generate OTP" button is clicked.

We will see how to design a basic GUI for the application and how to add functionality to it. Let's divide the code into 2 parts 1st the frontend GUI part and 2nd the backend functionality part.

The GUI part

As we will be implementing the GUI using Tkinter we will import the following libraries:

from tkinter import *
from tkinter import ttk

Now we will create a class otp and define the main function. Give a title to the window and set the window geometry as "1920x1080" as the size and "+0+0" are the starting coordinates from where the window will start. You can change these parameters as per your choice.

class otp:
    def __init__(self,window):
        self.window = window
        self.window.title("One Time Password login system")
        self.window.geometry("1920x1080+0+0")

Now we will create a frame in self.window as shown:

frame1 = Frame(self.window,bd=1,relief=RIDGE,bg="skyblue")
frame1.place(x=20,y=70,height=660,width=1300)

 we'll create a label and a button in the 'frame1' that we created earlier.

label1 = Label(frame1,text="Click on button to generate OTP ",bg="white",fg="black",font=("times new roman",20,"bold"))
label1.grid(row=4,column=2,padx=450,pady=50,sticky=W)

generate_button = Button(frame1,text="Generate OTP",height=2,width=11, command=generate_OTP)
generate_button.grid(row=5, column=2,pady=20,padx=10)

We will give window.mainloop to enable the window.

The working of OTP generation

Import random library because we'll be using it for otp generation. Create a function and in that create an empty list. Now 4 variables 'a,b,c and d' that will store random single-digit numbers from 0 to 9.

def generate_OTP():

            list1 = []

            a = random.randint(0,9)
            b = random.randint(0,9)
            c = random.randint(0,9)
            d = random.randint(0,9)

Now append all the variables one by one to the list created earlier and store the list in a variable called "otp" so that it can be used as it is later.

list1.append(a)
list1.append(b)
list1.append(c)
list1.append(d)
otp = list1

Now that we have generated the OTP we will now display it using the Label function.

label2 = Label(frame1,text=otp,bg="white",fg="black",font=("times new roman",20,"bold"))
label2.grid(row=6,column=2,padx=600,pady=50,sticky=W)

Lastly in the Button "Generate OTP" we will add 'command=generate_OTP' so that whenever the button is clicked the function is called and the OTP is generated.

Python Code

import random
from tkinter import *
from tkinter import ttk

class otp:
    def __init__(self,window):
        self.window = window
        self.window.title("One Time Password login system")
        self.window.geometry("1920x1080+0+0")
        
        title = Label(self.window,text="OTP login system",bd=0,font=("times new roman",30,"bold"),bg="white",fg="purple")
        title.pack(side=TOP,fill=X)

        def generate_OTP():

            list1 = []

            a = random.randint(0,9)
            b = random.randint(0,9)
            c = random.randint(0,9)
            d = random.randint(0,9)
            list1.append(a)
            list1.append(b)
            list1.append(c)
            list1.append(d)
            otp = list1
            

            label2 = Label(frame1,text=otp,bg="white",fg="black",font=("times new roman",20,"bold"))
            label2.grid(row=6,column=2,padx=600,pady=50,sticky=W)

         


        frame1 = Frame(self.window,bd=1,relief=RIDGE,bg="skyblue")
        frame1.place(x=20,y=70,height=660,width=1300)

        label1 = Label(frame1,text="Click on button to generate OTP ",bg="white",fg="black",font=(20))
        label1.grid(row=4,column=2,padx=450,pady=50,sticky=W)

        generate_button = Button(frame1,text="Generate OTP",height=2,width=11, command=generate_OTP)
        generate_button.grid(row=5, column=2,pady=20,padx=10)


window = Tk()
ob = otp(window)
window.mainloop()

 Application window

You can also convert this Python file to a .exe file so that it can run as an application.

Feel free to do any customizations or modifications.