How to make Custom Captcha Generator in CSS & JavaScript

Custom Captcha Generator

Custom Captcha is an anti-bot security feature that combines distorted letters and numbers. It is employed to differentiate between humans and automated bots. Its purpose is to restrict access to specific online features like registration or comment posting. The distorted characters pose a challenge that bots have difficulty solving.

Creating a captcha generator using HTML, CSS, and JavaScript could be quite an important skill for a developer. Whether you’re building a personal website or developing a client’s site.

The purpose of this blog post is to teach you how to develop a Captcha Generator using HTML, CSS, and JavaScript. Essentially, we’ll be designing a form that randomly generates a combination of letters and numbers in an unordered format. We’ll then need to fill in the correct letters to determine if we’ve accurately solved the captcha. By the end of this post, you’ll have gained the knowledge and skills needed to create and implement captchas on your own websites.

Steps For Creating Custom Captcha Generator in HTML

 Custom Captcha Generator
Custom Captcha Generator

To create a Custom Captcha generator using HTML, CSS, and vanilla JavaScript, follow the given steps line by line:

  1. Create a folder. You can name this folder whatever you want, and inside this folder, create the mentioned files.
  2. Create an index.html file. The file name must be index and its extension .html
  3. Create a style.css file. The file name must be style and its extension .css
  4. Create a script.js file. The file name must be script and its extension .js

To start, add the following HTML codes to your index.html file to create a basic layout for the captcha generator.

<!DOCTYPE html>
<!-- YouTube - CodingLab -->
<html lang="en">
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Captcha Generator</title>
    <link rel="stylesheet" href="style.css" />
    <!-- Fontawesome CDN Link -->
    <link rel="stylesheet" href="" />
    <div class="container">
      <header>Captcha Generator</header>
      <div class="input_field captch_box">
        <input type="text" value="" disabled />
        <button class="refresh_button">
          <i class="fa-solid fa-rotate-right"></i>
      <div class="input_field captch_input">
        <input type="text" placeholder="Enter captcha" />
      <div class="message">Entered captcha is correct</div>
      <div class="input_field button disabled">
        <button>Submit Captcha</button>

    <script src="script.js"></script>

Next, add the following CSS codes to your style.css file to style the Custom Captcha generator and make it interactive and beautiful.

/* Import Google font - Poppins */
@import url(";300;400;500;600;700&display=swap");
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: "Poppins", sans-serif;
body {
  height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  background: #826afb;
.container {
  position: relative;
  max-width: 300px;
  width: 100%;
  border-radius: 12px;
  padding: 15px 25px 25px;
  background: #fff;
  box-shadow: 0 5px 10px rgba(0, 0, 0, 0.1);
header {
  color: #333;
  margin-bottom: 20px;
  font-size: 18px;
  font-weight: 600;
  text-align: center;
.input_field {
  position: relative;
  height: 45px;
  margin-top: 15px;
  width: 100%;
.refresh_button {
  position: absolute;
  top: 50%;
  right: 10px;
  transform: translateY(-50%);
  background: #826afb;
  height: 30px;
  width: 30px;
  border: none;
  border-radius: 4px;
  color: #fff;
  cursor: pointer;
.refresh_button:active {
  transform: translateY(-50%) scale(0.98);
.input_field input,
.button button {
  height: 100%;
  width: 100%;
  outline: none;
  border: none;
  border-radius: 8px;
.input_field input {
  padding: 0 15px;
  border: 1px solid rgba(0, 0, 0, 0.1);
.captch_box input {
  color: #6b6b6b;
  font-size: 22px;
  pointer-events: none;
.captch_input input:focus {
  box-shadow: 0 1px 1px rgba(0, 0, 0, 0.08);
.message {
  font-size: 14px;
  margin: 14px 0;
  color: #826afb;
  display: none;
} {
  display: block;
.button button {
  background: #826afb;
  color: #fff;
  cursor: pointer;
  user-select: none;
.button button:active {
  transform: scale(0.99);
.button.disabled {
  opacity: 0.6;
  pointer-events: none;

Finally, add the following JavaScript code to your script.js file to make the to generate random Custom Captcha and validated our entered captcha.

// Selecting necessary DOM elements
const captchaTextBox = document.querySelector(".captch_box input");
const refreshButton = document.querySelector(".refresh_button");
const captchaInputBox = document.querySelector(".captch_input input");
const message = document.querySelector(".message");
const submitButton = document.querySelector(".button");

// Variable to store generated captcha
let captchaText = null;

// Function to generate captcha
const generateCaptcha = () => {
  const randomString = Math.random().toString(36).substring(2, 7);
  const randomStringArray = randomString.split("");
  const changeString = => (Math.random() > 0.5 ? char.toUpperCase() : char));
  captchaText = changeString.join("   ");
  captchaTextBox.value = captchaText;

const refreshBtnClick = () => {
  captchaInputBox.value = "";

const captchaKeyUpValidate = () => {
  //Toggle submit button disable class based on captcha input field.
  submitButton.classList.toggle("disabled", !captchaInputBox.value);

  if (!captchaInputBox.value) message.classList.remove("active");

// Function to validate the entered captcha
const submitBtnClick = () => {
  captchaText = captchaText
    .filter((char) => char !== " ")
  // Check if the entered captcha text is correct or not
  if (captchaInputBox.value === captchaText) {
    message.innerText = "Entered captcha is correct"; = "#826afb";
  } else {
    message.innerText = "Entered captcha is not correct"; = "#FF2525";

// Add event listeners for the refresh button, captchaInputBox, submit button
refreshButton.addEventListener("click", refreshBtnClick);
captchaInputBox.addEventListener("keyup", captchaKeyUpValidate);
submitButton.addEventListener("click", submitBtnClick);

// Generate a captcha when the page loads

Conclusion and Final Words

I hope this blog post taught you how to make your own Custom Captcha Generator using HTML, CSS, and JavaScript. The coding process is simple and easy to understand, so you can customize your generator to your needs.

With this skill, you can make your website more secure and prevent spam or hacking. I’m confident that this post gave you the tools and confidence to create a great Captcha Generator. I recommend you to check my blog on Strong Password Generator in HTML CSS & JavaScript. This will also help you to enhance you JavaScript skills.

If you face any difficulties while creating your own captcha generator or your code is not working as expected, you can download the source code files for this captcha generator for free by clicking on the download button, and you can also view a live demo of this card slider by clicking on the view live button.

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