DEV Community

Cover image for How to implement CAPTCHAs or reCAPTCHAs?
Code of Relevancy
Code of Relevancy

Posted on • Updated on


How to implement CAPTCHAs or reCAPTCHAs?

Welcome to Code of Relevancy.

What is reCAPTCHA?

reCAPTCHA is an advanced security system that uses sophisticated algorithms to discern between humans and machines. It does this by offering users a range of puzzles or quizzes, making it difficult for automated scripts and bots to access the platform without being identified first. reCAPTCHA provides users with a more secure and reliable online experience through its innovative technology, allowing them to authenticate with ease.

I have been using reCAPTCHA for a few years now and I can attest to its efficacy. Not only does it offer reliable security, but also makes sure that the user experience is not hampered in any way. It's become an essential tool when browsing online, as no one wants their information or data being stolen by malicious individuals. As someone who has seen firsthand how effective this technology is, I'm personally impressed with the accuracy of reCAPTCHA and can recommend it to anyone looking for added protection on their digital devices.

The unique thing about reCAPTCHA is that it’s constantly evolving and improving itself. With each new version released, we get access to better algorithms and more sophisticated methods of authentication. It’s made possible through the application of machine learning and artificial intelligence, which allows reCAPTCHA to continually improve its accuracy and become increasingly difficult for malicious actors to evade.

What is reCAPTCHA v3?

reCAPTCHA v3 uses advanced risk analysis techniques to determine the likelihood that a user is a human or a bot. Instead of presenting a user with a CAPTCHA challenge, it returns a score between 0.0 and 1.0, with a higher score indicating that the user is more likely to be a human. This allows website owners to take appropriate action based on the risk level. For example, they might allow users with a high score to pass through without any additional checks, while requiring users with a lower score to complete a CAPTCHA challenge or take some other action to verify their humanity.

Implementing CAPTCHAs or reCAPTCHAs requires a certain level of skill and precision. One must accurately gauge the complexity of the challenge to ensure it is both secure yet accessible enough for legitimate users to complete. For instance, when designing a CAPTCHA you could use a combination of letters, numbers, symbols and emojis as part of your challenge, but then there is the question of how many characters do you ask them to input? Too few might be too easy to bypass while too many may make it difficult for real people to solve. Additionally, you should choose an uncommon word that can't easily be guessed by bots - this will help to ensure the integrity of your security system.

To implement CAPTCHAs or reCAPTCHAs, follow these steps:

  1. Sign up for an account with Google reCAPTCHA: Google reCAPTCHA

  2. Select "reCAPTCHA v2" and specify the type of CAPTCHA you want to use (e.g. checkbox, invisible, etc.). Or select "reCAPTCHA v3".

Image description

  1. Follow the instructions to register your website and get the necessary site key and secret key

  2. Add the reCAPTCHA code to your website HTML, using the site key provided by Google

Image description

  1. When a user submits a form on your website, validate the CAPTCHA by making a request to the reCAPTCHA server using the secret key and the user's response token

  2. If the CAPTCHA is valid, allow the form submission to proceed. If it is not valid, show an error message or take other appropriate action.

Client side integration for reCAPTCHA v3:

reCAPTCHA v3 will never interrupt your users, so you can run it whenever you like without affecting conversion. reCAPTCHA works best when it has the most context about interactions with your site, which comes from seeing both legitimate and abusive behavior. For this reason, I recommend including reCAPTCHA verification on forms or actions as well as in the background of pages for analytics.

Adding reCAPTCHA v3 to your page is straightforward: simply include the necessary JavaScript resource and add some attributes to your HTML button. By doing so, you'll benefit from a more secure environment that helps keep malicious bots at bay while maintaining an easy user experience. An added advantage of using reCAPTCHA v3 is its ability to detect suspicious activity without requiring any action from the user — no need to check boxes or type text — making it ideal for creating efficient digital experiences with minimal disruption.

1. Load the JavaScript API.

<script src=""></script>
Enter fullscreen mode Exit fullscreen mode

2. Add a callback function to handle the token.

   function onSubmit(token) {
Enter fullscreen mode Exit fullscreen mode

3. Add attributes to your html button.

<button class="g-recaptcha" 
Enter fullscreen mode Exit fullscreen mode

Programmatically invoke the challenge

If you're looking to gain greater command over when reCAPTCHA runs, the grecaptcha object's execute method can be used. To make this happen, add a render parameter to your reCAPTCHA script load. This will grant you the power to administer reCAPTCHA at your own discretion.

1. Load the JavaScript API with your sitekey.

<script src=""></script>
Enter fullscreen mode Exit fullscreen mode

2. Call grecaptcha.execute on each action you wish to protect.

      function onClick(e) {
        grecaptcha.ready(function() {
          grecaptcha.execute('reCAPTCHA_site_key', {action: 'submit'}).then(function(token) {
              // Add your logic to submit to your backend server here.
Enter fullscreen mode Exit fullscreen mode

3. Send the token immediately to your backend with the request to verify.

I think Google reCAPTCHA is a fantastic and important tool for every website, but it's always worth taking a second to think about what makes your digital experience truly unique and meaningful. We all have our own stories to tell; how can you use reCAPTCHA in ways that allow those stories to be told? Get creative! Incorporate the text challenge or mini-games into interactive pages so they become part of the user experience instead of just an obstacle.

Please consider following and supporting me by subscribing to my channel. Your support is greatly appreciated and will help me continue creating content for you to enjoy. Thank you in advance for your support!


Top comments (2)

Some comments may only be visible to logged-in visitors. Sign in to view all comments.

An Animated Guide to Node.js Event Loop

Node.js doesn’t stop from running other operations because of Libuv, a C++ library responsible for the event loop and asynchronously handling tasks such as network requests, DNS resolution, file system operations, data encryption, etc.

What happens under the hood when Node.js works on tasks such as database queries? We will explore it by following this piece of code step by step.