How to write a test case for captcha?

February 28, 2024Hariharan Dhanraj
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What is a Captcha?

In our interconnected world, where the internet has become an integral part of our daily lives, the importance of data security has risen to sky heights. We have all heard the tales of thieves targeting personal belongings of people and scammers employing devious tactics to steal information and money from the general public. 

However, in this digital age, these threats extend beyond human adversaries. The rise of sneaky bots has added a new dimension to the challenge.

As the internet expanded, so did the shadowy presence of bots. Let’s say these bots are like cosmic threats in superhero tales, that seek to exploit the vulnerabilities and disrupt the peace in the Internet world. 

“Enter CAPTCHAs”, or “Completely Automated Public Turing tests to tell Computers and Humans Apart.”  does the role of a digital guardian. Think of it as a puzzle, meticulously designed to separate the  human users from the crafty bot invaders to ensure the internet remains a secure and user-friendly realm.

This digital puzzle was created to confirm if a real person was using a website or not. At the beginning , it was more like a simple math question, for example, “What is 2 + 2?” 

The idea was to make it easy for people but tricky for computer programs.

 Imagine CAPTCHA as our online guardian using this puzzle. If someone gave the right answer, like ‘4,’ it meant they were a real person, and the system let them in and allowed them to access information or continue to use the application. On the other hand if someone intentionally gave the wrong answer, like ‘5,’ it was a test to see if the CAPTCHA could spot the trick and firmly say, “No entry!” or “Invalid” 

As technology advanced, bots got smarter at answering simple questions. To stay ahead, more advanced versions of CAPTCHA appeared, featuring things like tricky visual puzzles, distorted letters, and even image recognition challenges.

The secret to a CAPTCHA’s success lies in finding the perfect balance – it should be tough enough to stump bots but still doable for humans. It’s an ongoing battle as technology evolves on both sides.


How Do You Write a CAPTCHA Test?

Many of us have come across CAPTCHAs when trying to access websites. They can be simple math problems or image recognition tasks, among other types. Let’s explore how we create test cases for CAPTCHAs. The testing team plays a crucial role in ensuring CAPTCHAs work correctly, as they are part of the software’s security measures.

Try  these scenarios:

  • Scenario 1: Ensure CAPTCHA functionality by solving a simple math problem.
  • Scenario 2: Validate CAPTCHA’s security by intentionally providing the wrong answer.
  • Scenario 3: Test CAPTCHA’s ability to detect and block sneaky bots.
  • Scenario 4: Evaluate CAPTCHA’s timed feature to balance security and efficiency.

Testing CAPTCHA Functionality should include:

  • Verify CAPTCHA Presence and Alignment: Check if CAPTCHA is on the webpage and aligned correctly.
  • Assess Loading Time: Measure how quickly CAPTCHA loads on the webpage.
  • Reload Page Test: Ensure that reloading the page generates a new CAPTCHA.
  • Compatibility with Ad Blockers: Check if CAPTCHA displays correctly with ad blockers.
  • Test on Adblocker-Equipped Browsers: Validate CAPTCHA functionality on browsers with ad blockers.
  • Validate Acceptance of Valid CAPTCHA: Confirm that the webpage accepts a valid CAPTCHA.
  • Check for Audio Option: Ensure that an audio option is available for CAPTCHA.
  • Error Handling: Test error handling for incorrect or missing CAPTCHAs.
  • IP Blocking: Verify if IP blocking occurs after a defined number of invalid CAPTCHA attempts.
  • CAPTCHA Code Validation: Check CAPTCHA code visibility, format, and non-disruptiveness in the form.

These tests help ensure that CAPTCHA serves its purpose of distinguishing humans from automated scripts effectively while maintaining a secure and user-friendly online experience.

Explore Writing a CAPTCHA Test in detail 

Writing a CAPTCHA test involves a thoughtful combination of diverse challenges, accessibility considerations, and periodic updates to fortify its effectiveness in distinguishing between humans and bots while safeguarding online platforms.

Include Different Task Types:

  • Visualize your CAPTCHA as a vigilant protector of online payments. Incorporate a straightforward math question into the verification process to confirm the accuracy of transaction details. 
  • Implement an image recognition task to validate the user’s visual confirmation, ensuring a secure and accurate payment experience. 
  • Additionally, include a checkbox affirmation to solidify the user’s genuine intent and commitment to a safe transaction. 
  • This multifaceted CAPTCHA transforms into a dynamic defender, fortifying the security of online payments by engaging users in varied and effective verification measures.

Audio and Visual Challenges: 

  • Improve accessibility by presenting visual challenges tied to payment icons or images, accompanied by audio instructions to seamlessly guide users through a secure transaction process. 
  • This inclusive approach allows a diverse user base to navigate the CAPTCHA process with ease and reinforces the protection of their online transactions.

Checkbox Verification:

  • Checkbox verification in CAPTCHA serves as a user’s virtual confirmation, ensuring their commitment to a secure online experience.
  • By simply checking the box, users affirm their genuine intent, adding an extra layer of security to the process. It’s like a digital nod, assuring that the user is ready for a safe online transaction.

Time Constraints:

  • The concept of “Time Constraints” in CAPTCHA testing simulates a scenario where users have a limited amount of time to complete a CAPTCHA challenge before they can proceed with an online transaction or access a secured digital area. 
  • This time limit is in place to ensure that users confirm their identity quickly and efficiently, which is essential for maintaining the security of digital transactions. 
  • In simpler terms, it tests whether users can solve the CAPTCHA puzzle within a short timeframe to prevent any potential security risks associated with prolonged authentication processes. It’s like a fast but necessary security checkpoint to protect online payments and sensitive digital interactions.

Frequently Change Challenges:

  • Think of CAPTCHA challenges like changing locks on your door to keep your home secure. By regularly introducing new types of security puzzles, it becomes harder for intruders to figure out how to break in. 
  • It’s similar to having a smart security system that’s always updated and ready to defend your online payments from any potential threats, making sure they stay safe and easy for you.

Test Cases For CAPTCHA

When it comes to Online security, Captchas act as gatekeepers, ensuring real users breeze through while stopping the automated bots. Let’s take a look into some simple yet effective ways to test Captcha functionality, ensuring both security and a smooth user experience.

Generic Test Cases for Captcha Functionality

Imagine test cases as tools we use to check how well Captchas work. These test cases are like helpful guides, making sure Captchas can tell humans from bots and making it easy for users to complete tasks.

Answer Validation:

  • Provide the correct solution to the Captcha puzzle, showcasing your ability to decipher the presented challenge effortlessly. For instance, if the Captcha poses a mathematical question like “What’s 3 + 4?”, respond with the accurate answer, “7.”

Handling Incorrect Answers:

  • Challenge the system by intentionally entering an incorrect response to the Captcha. For example, if the puzzle expects the name of a fruit, input something unrelated like “car.”

Timeout Verification:

  • Test the Captcha’s timeout feature by deliberately delaying your response. This helps ensure that the Captcha imposes a time limit, prompting users to either refresh or attempt a new challenge after a certain duration.

Audio Challenge Accessibility:

  • Explore the accessibility aspect by engaging with an audio-based Captcha challenge. Click on the sound icon and enter the numbers or information presented in the auditory component, ensuring an inclusive experience for users with visual impairments.

Refreshing Challenge:

  • Check the system’s response to a refreshed Captcha. Click the refresh button to generate a new puzzle, validating that the system offers varied challenges and prevents the reuse of the same Captcha.

Multiple Failed Attempts:

  • Evaluate the system’s response to consecutive failed attempts. Intentionally provide incorrect answers several times in a row, observing how the Captcha handles and potentially restricts access to deter automated bots.

Responsive Design Check:

  • Assess the responsiveness of the Captcha by solving it on different devices. Confirm that the puzzle adapts well to various screen sizes, providing a consistent and user-friendly experience.

Cross-Browser Compatibility:

  • Ensure the Captcha functions seamlessly across different web browsers. Solve the challenge using browsers like Chrome, Firefox, and Safari, verifying compatibility to guarantee a uniform experience for users.

Dynamic Challenge Variation: 

  • Observe how Captcha challenges dynamically change. Solve multiple puzzles consecutively, refreshing the page to witness different challenges each time, enhancing security by preventing pattern recognition.

Accessibility Mode Testing:

  • Turn on accessibility features to assess the Captcha’s inclusivity. Confirm that the system provides alternative options for users with visual impairments, aligning with accessibility standards.

Test cases for Text Captcha

Text Recognition & Case Sensitivity:

  • Ensure that the Text Captcha accurately recognizes and validates the entered text, considering variations in letter casing. This encompasses verifying the system’s ability to identify the presented text and distinguishing between uppercase and lowercase characters.

Numerical and Special Characters Handling:

  • Explore how well Text Captchas handle challenges involving numbers and special characters. 
  • This test involves validating the system’s recognition and acceptance of numeric and character inputs, ensuring versatility in processing various text components.

Whitespace and Long Text Management:

  • Assess how Text Captchas manage challenges with spaces and handle longer strings of text. 
  • This test focuses on the system’s ability to handle whitespace appropriately and process and validate inputs, even when presented with extended sequences.

Refresh Functionality & Timeout Mechanism:

  • Evaluate how the Captcha responds to refresh requests and the timeout mechanism. Confirm that clicking on the refresh button generates a new challenge, preventing the reuse of the same Text Captcha.
  •  Additionally, explore how the system handles timeouts, enhancing security with prompt user interactions.

Multilingual Support & Dynamic Text Variations:

  • Test Captcha’s multilingual support: Confirm that Text Captchas can handle challenges in languages beyond English.
  • Assess dynamic variations: Ensure Captcha adapts and changes its challenges, altering text wording, structure, or format.
  • Prevent pattern recognition: The goal is to thwart bots by preventing them from recognizing a consistent pattern.
  • Clever chameleon strategy: Captcha should be versatile in languages and appearance to outsmart sneaky bots.
  • Double-layered defense: Captcha employs linguistic versatility and dynamic challenges to guard online spaces effectively.

Test Cases for Image Captcha

Spot-on Image Recognition:

  • In this test, imagine the Captcha displaying images of common objects like a cat, a car, and a tree. Users would need to correctly identify each object and input their names, such as “cat,” “car,” and “tree,” in the corresponding text boxes. Success is achieved when the Captcha accurately recognizes and validates these correct responses.

Mix and Match Objects:

  • Consider the Captcha presenting a mix of objects like a key, a balloon, and a book. Users have to efficiently identify and give the input names of these diverse objects – “key,” “balloon,” and “book” correctly.
  • The Captcha’s effectiveness is demonstrated when it accurately validates the user’s responses, showcasing its adaptability to various visual challenges.

Choose 3 out of 5 Structures:

  • Some image captchas might present a grid of 5 structures and ask users to choose the correct ones, adding an element of selection. 
  • Users succeed by identifying and selecting the right structures based on the instructions provided. The Captcha proves successful when it accurately validates the user’s chosen structures, ensuring precision in the selection process.

Colors and Contrasts Check:  

  • In this test, the Captcha might display images with subtle color and contrast differences, such as a red apple against a green background. Users can pass this by spotting these correctly and entering the corresponding names, like “apple.” 
  • The Captcha’s success is evident when it appropriately recognizes and validates responses, showcasing its sensitivity to color and contrast changes.

Challenges with Rotated Images:

  • Imagine the Captcha introducing challenges with images at different angles, like a tilted cup or a sideways chair. Users can effortlessly identify these objects and enter their names, such as “cup” and “chair.” 
  • Success is confirmed when the Captcha accurately recognizes and validates responses, demonstrating its competence in handling rotated or oriented images.

Refreshing Dynamic Challenges:

  • Upon hitting refresh, the Captcha presents a new set of images, perhaps a bicycle, a cloud, and a sandwich. Users have to correctly identify and enter the names of these fresh challenges – “bicycle,” “cloud,” and “sandwich.” 
  • The Captcha’s success lies in consistently serving up dynamic challenges, ensuring unpredictability for potential bots and maintaining a secure online environment.

Test Cases for Audio Captcha

Decipher Spoken Numbers, Letters, and Background Noise Resilience:

  • Users face an Audio Captcha presenting a sequence of spoken numbers and letters. 
  • Imagine you’re in a busy café, and you encounter an Audio Captcha with spoken numbers and letters. Your task is not just to transcribe it accurately but to do so amidst the cafe’s background noise. Success means accurately entering the code, proving that the Captcha works effectively in real-world situations.

Multiple Choice Challenges:

  • In certain scenarios, Audio Captchas provide multiple spoken options. Users encounter spoken sequences and must select the correct one. 
  • Think of it as a game show where the contestant listens attentively and picks the right answer. 
  • Success here involves accurate listening and choosing the right sequence from the provided options, highlighting the Captcha’s flexibility in presenting challenges.

Speedy Responses and Dynamic Challenge Variations:

  • Users may encounter a time-sensitive Audio Captcha, adding an element of urgency. Picture a fast-paced quiz where contestants must respond promptly. 
  • Success is achieved when users swiftly and accurately enter the spoken sequence within the allotted time, testing the Captcha’s efficiency in time-sensitive scenarios. 
  • Additionally, refreshing the Captcha introduces new spoken sequences, enhancing unpredictability and ensuring users stay on their toes to meet evolving challenges.

Test Cases for Video Captcha

Mastering Sequence Recognition and Dynamic Object Tracking: 

  • Successfully navigating Video Captcha begins with users accurately identifying dynamic visual sequences and tracking moving objects within the video. 
  • Imagine spotting a sequence of changing colors or a moving target within the dynamic visuals – this is the challenge users conquer.

Interactive Scavenger Hunt and Selective Element Recognition:

  • Users triumph by engaging in an interactive scavenger hunt, following and identifying moving objects. Simultaneously, challenges may require users to selectively choose specific elements from dynamic scenes.
  • Picture tracking a playful animal amidst a changing backdrop and selecting the right elements from a vibrant scene – users excel by mastering these visual puzzles.

Spatial Intelligence Challenge:

  • Video Captcha scenarios may demand users to understand spatial relationships between visual elements. 
  • Success involves comprehending and entering the correct spatial arrangement – think of it as arranging digital puzzle pieces to unlock the visual intelligence challenge.

Continuous Visual Adventure with Dynamic Challenge Variations:

  • Refreshing the Video Captcha introduces ever-evolving challenges, transforming the experience into a continuous visual adventure. 
  • Users decipher new sequences or arrangements with each refresh, ensuring an engaging and secure verification process. 
  • Consider encountering different dynamic scenes or rearrangements in each challenge.

Test Cases for Puzzle Captcha

Strategic Puzzles and Dynamic Arrangements:

  • Think of Puzzle Captcha as a digital escape room. Users face challenges like arranging virtual objects or solving puzzles, similar to unlocking clues in an escape room. 
  • The dynamic arrangement ensures each user encounters a unique puzzle, making it tricky for automated bots to predict and solve.

Adding Complexity with Patterns and Symmetry:

  • Consider a user navigating a maze. In the digital realm, Puzzle Captcha introduces pattern recognition tasks akin to finding the correct path in a maze. 
  • Rotational symmetry challenges can be compared to arranging objects symmetrically, mirroring the precision needed in real-world tasks.

Colors and Ongoing Innovation:

  • Imagine organizing a vibrant bookshelf by color or arranging LEGO blocks to create a visually appealing structure. Puzzle Captcha’s color-driven complexity is like organizing these elements digitally. 
  • Continuous innovation ensures challenges remain as diverse and unpredictable as real-life situations.

User-Friendly Complexity:

  • Picture a board game that is challenging yet enjoyable for players of different ages. Puzzle Captcha, similarly, aims for a user-friendly experience. 
  • Designing challenges is akin to creating engaging game levels, ensuring users not only pass security checks but also find the puzzle-solving process enjoyable.

Test Cases for ReCaptcha

Human-Like Interaction Simulation:

  • Picture users going through a digital obstacle course in ReCaptcha, like completing a fun online challenge. 
  • The system checks if it can recognize how people naturally move the mouse and click. 
  • It wants to be friendly to humans but tricky for bots. Although bots can copy basic mouse actions, they usually miss the subtle and natural behaviors real people have. 
  • Things like different speeds, pauses, or unpredictable patterns are more common in human interaction. ReCaptcha is good at noticing these small details, helping it tell the difference between bots and real users, enhancing its effectiveness as a security measure.

Decoding Audio Challenges with Ease:

  • Imagine people listening to a short audio clip with a scrambled message. We design situations to make sure users easily get what’s being said, ensuring it’s user-friendly for everyone. 
  • While bots can kind of understand audio challenges, ReCaptcha is great because it makes tricky situations with language differences, accents, or background noise that bots find hard to figure out. 
  • ReCaptcha’s strength is creating diverse and complex audio challenges that imitate real-life variations, making it tough for bots to act like humans.

Identifying Objects in Image Challenges:

  • Picture users picking out certain things in a picture, like finding something in a busy scene. ReCaptcha’s good at making sure users can accurately choose the right things, showing it can tell humans apart from bots. 
  • While bots might try to figure out specific items in pictures, ReCaptcha makes it tricky by using cluttered or subtly detailed images.
  • ReCaptcha works well because it designs visual challenges that need a human-like understanding, making it tough for bots to pick the right things in varied and complicated scenes.

Mobile-Friendly :

  • Ensure ReCaptcha seamlessly integrates with mobile devices. Picture users tackling challenges on their smartphones, akin to solving a mobile puzzle. 
  • Test various scenarios on different mobile platforms to ensure a smooth process on both desktop and mobile.

Browser Harmony Check:

  • Confirm that ReCaptcha plays nice with various web browsers. Visualize users accessing a website using Chrome, Firefox, or Safari. 
  • Test the challenges to guarantee a consistent, hassle-free experience, regardless of the browser they opt for.

Invisible ReCaptcha

  • Invisible ReCaptcha is an advanced version of Google’s ReCaptcha technology designed to secure websites from automated bots without requiring any visible interaction from users. 
  • Unlike traditional ReCaptcha, where users often need to solve puzzles or click checkboxes, Invisible ReCaptcha works in the background, silently analyzing the difference between real people and bots by looking at how users move their mouse, click around, and use the website. 
  • It checks for natural and varied behavior, as humans tend to act differently than programmed bots. 
  • This helps Invisible ReCaptcha stop unwanted bots without bothering real users. It enhances security without causing any noticeable disruptions to the user experience, making the verification process seamless and transparent.

Human-Like Actions Check: 

  • See how well it spots actions that look like humans, without needing them to do anything specific.

Smart Against Tricky Bots: 

  • Test if it can handle new tricks from bots and change its strategies, all without asking users to do anything special.

Spotting Quiet Interactions: 

  • Check if it can notice small signs in how users interact, telling apart real people from scripted bots.

Adapting to Users: 

  • Test how it reacts to different things users do, adjusting its security without bothering them.

Quietly Protecting: 

  • Confirm that it keeps websites safe in the background, all without making users do anything noticeable

ReCaptcha enterprise 

  • ReCAPTCHA and reCAPTCHA Enterprise, both geared towards safeguarding digital platforms, vary in scale and features. 
  • While ReCAPTCHA is tailored for smaller websites with challenges like image recognition, ReCAPTCHA Enterprise caters to larger enterprises with advanced features like adaptive risk analysis and customizable challenges, providing heightened protection. 
  • These test cases will focus on assessing the system’s adaptability to challenges and continuous monitoring capabilities, simulating real-world threats such as credential stuffing and automated account creation. 
  • This comprehensive evaluation ensures the system’s robustness in distinguishing genuine users from potential security threats.

Dynamic Adaptability and Behavioral Analysis:

  • Craft test cases that examine ReCaptcha Enterprise’s dynamic adaptability and behavioral analysis. Simulate varied user behaviors to ensure the system tailors challenges dynamically while accurately categorizing human and automated interactions.

Machine Learning Effectiveness and Risk Assessment Accuracy:

  • Focus on testing scenarios that evaluate the effectiveness of ReCaptcha Enterprise’s machine learning algorithms and its risk assessment accuracy. Introduce diverse attack scenarios to assess the system’s ability to evolve, respond to threats, and accurately categorize risks.

Frictionless User Experience and Continuous Learning:

  • Prioritize test cases that balance robust security with a seamless user experience. Evaluate the system’s ability to minimize disruptions for genuine users while continuously learning and adapting to evolving attack patterns.

Insightful Analytics, Integration, and Scalability:

  • Validate the accuracy of ReCaptcha Enterprise’s analytics and its integration with enterprise applications. 
  • Design test cases that assess the system’s performance under varying loads, ensuring scalability and reliable integration with diverse platforms.

Accessibility Compliance:

  • Ensure your test cases cover ReCaptcha Enterprise’s accessibility compliance.
  •  Evaluate its performance with users of diverse abilities, confirming that the system is inclusive and accessible while maintaining security measures.

Can you automate the testing of CAPTCHA?

  • Yes, it’s possible to automate CAPTCHA testing, but it comes with challenges. Automated testing involves scripts designed to analyze and recognize distorted characters, essentially simulating human-like responses. 
  • This includes using algorithms, image recognition, or other techniques to simulate how a person would solve or interact with the CAPTCHA. 
  • However, in scenarios where CAPTCHAs employ more complex elements intentionally designed to challenge automated scripts, manual intervention may be required to ensure accurate verification.
  • For example, if the CAPTCHA involves identifying objects in images or dealing with more intricate visual elements that automated scripts find challenging, a human reviewer steps in to validate the accuracy of the user’s response. 
  • This ensures a higher level of precision in distinguishing between human users and automated bots for complex challenges that automated scripts might struggle with. 
  • So, while automated scripts can handle certain types of CAPTCHAs, manual intervention becomes necessary for more complex or uniquely designed challenges. It’s a dynamic balance between automated tools and human judgment to ensure effective security

How to Automate Test Cases for Captcha with Testsigma?

Best Practices for Test Cases:

  • Clear Purpose and Thoroughness:
    • Identify the purpose of your test case and what needs testing.
    • Write clear and concise test cases with step-by-step instructions.
    • Consider various scenarios and edge cases for comprehensive testing.
  • Organized Testing Process:
    • Maintain an organized structure with a logical flow of tests.
    • Cover different aspects of the system in your testing.
  • Regular Review and Refinement:
    • Periodically review and refine your test cases for quality.
  • CAPTCHA Handling:
    • Understand that CAPTCHAs are designed to prevent automation.
    • Implement workarounds like configuring CAPTCHA in the test environment or disabling it for testing purposes.
    • Collaborate with developers to generate APIs or access CAPTCHA codes for testing.

Test Cases for CAPTCHA:

  • Verify CAPTCHA presence on the login page.
  • Check if CAPTCHA regenerates when required.
  • Test CAPTCHA refresh options for user accessibility.
  • Validate CAPTCHA input prevention and timeouts.
  • Ensure CAPTCHA accessibility through alternative text or audio.

Testsigma provides robust support for cross-browser testing, allowing you to ensure that your CAPTCHA works seamlessly across various web browsers and devices. With the ability to test on over 3000 browser and device combinations, Testsigma ensures that the end user experience remains consistent and reliable.

Additionally, Testsigma offers visual testing capabilities, enabling you to verify the correct placement of CAPTCHA elements and the overall UI aspect of your web pages. This low-code visual testing automation helps uncover any visual defects that functional tests might overlook, enhancing the overall quality of your CAPTCHA implementation.

Furthermore, Testsigma allows you to perform both UI and functional tests in parallel with just one click. This streamlined approach ensures efficient testing across a wide range of web and mobile devices, providing comprehensive coverage for your CAPTCHA testing needs.

Testsigma’s highlight features also include: 

  • Easy Automation: Automate tests using plain English, making it accessible for non-technical team members.
  • Multi-Platform Support: Automate tests across web, mobile, API, and desktop applications from a single platform.
  • AI-Powered: Utilize AI for test maintenance, bug reporting, and optimization.
  • Cloud Execution: Execute tests on the cloud, with scalable cloud device lab connections.
  • Comprehensive Testing: Conduct data-driven, image recognition-based testing on local and cloud devices, with 24/7 support for issue resolution.


In the world of online security, CAPTCHA acts as a vigilant guardian, protecting digital spaces from unwanted bots. It does this by distinguishing between real humans and automated scripts. Creating effective test cases for CAPTCHA can be a challenge, especially with the increasing complexity of CAPTCHAs.

Sometimes, automated tools work well, but for the most intricate CAPTCHAs, human verification may be necessary. Striking a balance between automated solutions and human judgment is crucial in building a strong defense against unwanted bots in our ever-changing online world. Whether it’s deciphering distorted text or identifying objects in images, mastering and testing CAPTCHAs is essential in strengthening the security of the websites and apps we use every day.

Frequently Asked Questions

How do I test Google CAPTCHA?

To integrate Google’s reCAPTCHA V3 into your application, follow these steps on both the client and server sides. First, obtain your site key and secret key by completing the Google form for reCAPTCHA API integration.

Client-Side (Frontend) :

1) Add the reCAPTCHA script to your HTML file within the <head> tag.
<script src=”https://www.google.com/recaptcha/api.js” async defer></script>

2) Create a form or container using HTML elements like <form> or <div> to display the captcha.
<form class=”g-recaptcha” data-sitekey=”YOUR_SITE_KEY” onSubmit = {API_CALL_TO_SERVER}></form>

3) Upon clicking submit, make an API call to the server with necessary details, including the captcha token received after the user solves the captcha puzzle.

Server-Side (Backend):

1) On the server side, create an endpoint (‘/submit-form’) to verify the reCAPTCHA response using your secret key to ensure validation of the user’s response to prevent fraudulent submissions.

2) In the provided Node.js and Express example, when the client hits the ‘/submit-form’ endpoint, retrieve the details passed and make a captcha API verify call to Google for validation.

3) On successful validation, allow the user to submit the form and proceed.

Sample server code  : 

const express = require(‘express’);

const app = express();

app.post(‘/submit-form’, async (req, res) => {

  const recaptchaToken = req.body;

  const secretKey = ‘YOUR_SECRET_KEY’;

  const verificationURL = ‘https://www.google.com/recaptcha/api/siteverify’;

try {

    const response = await fetch(verificationURL , {

method : ‘POST’,

body:  {
  secret:  secretKey,
              response: recaptchaToken,

    const validatedResponse = response.json()

    const { success } = validatedResponse .data;

    if (success) {

      res.send(‘Form submitted successfully!’);

    } else {

      res.status(400).send(‘reCAPTCHA verification failed.’);


  } catch (error) {

    res.status(500).send(‘Internal Server Error’);



const PORT = process.env.PORT || 3000;

app.listen(PORT, () => {

  console.log(`Server is running on port ${PORT}`);


What type of test is CAPTCHA?

CAPTCHA, or Completely Automated Public Turing test to tell Computers and Humans Apart, serves as a vital security test. Its purpose is to distinguish between automated bots and human users, ensuring that interactions with a system are genuine and not exploited by computer programs. In broader terms, CAPTCHA (security tests) are crucial measures ensuring the integrity and safety of digital interactions.

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