Solve reCAPTCHA with JavaScript: A Complete Tutorial

6 min readAug 21, 2024

While reCAPTCHA effectively safeguards web content, it can sometimes hinder legitimate activities, such as research, data analysis, or other compliance-driven automation tasks that involve interacting with web services.

What You Will Learn

So in this blog, we will walk you through the steps needed to solve reCAPTCHA challenges using JavaScript. You’ll learn how to set up your development environment, use Puppeteer to interact with web pages, and implement solutions for both reCAPTCHA v2 and v3. By the end of this tutorial, you’ll have a strong understanding of how to programmatically solve reCAPTCHA challenges, allowing you to integrate this knowledge into your own projects.

What is reCAPTCHA ?

reCAPTCHA is a type of CAPTCHA that helps distinguish human users from bots by presenting challenges that are simple for humans but difficult for machines. Over the years, reCAPTCHA has evolved from distorted text that users need to type in, to more complex image-based puzzles, and now to an almost invisible version that runs in the background, scoring users based on their behavior on the site.

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Versions of reCAPTCHA:

reCAPTCHA v2: This version is widely recognized for its “I’m not a robot” checkbox and image-based challenges. It requires users to click on images or verify certain actions, making it effective for distinguishing humans from bots.

reCAPTCHA v3: Unlike v2, reCAPTCHA v3 is invisible and works in the background. It assesses users’ interactions on a website and assigns a score based on how likely it is that the user is a bot. Websites can then use this score to decide whether to allow or block the user.
reCAPTCHA Enterprise: For businesses with higher security needs, reCAPTCHA Enterprise showing up. This version provides advanced protection against sophisticated threats, integrating more deeply with enterprise-level security measures. It includes enhanced risk analysis, customizable scoring, and better scalability, making it suitable for organizations handling sensitive data or critical operations.

Why Solve reCAPTCHA with JavaScript?

For developers working on projects like web scraping, automated testing, or form automation, encountering reCAPTCHA can be a significant roadblock. Manually solving reCAPTCHA every time is not feasible in automation scenarios, which is where JavaScript comes into play. By leveraging JavaScript, specifically with the help of tools like Puppeteer, developers can programmatically interact with and solve reCAPTCHA challenges.

Common Use Cases:

1. Web Scraping: Extracting data from websites often involves interacting with forms or pages protected by reCAPTCHA.
2. Automated Testing: Ensuring the stability of web applications may require automated form submissions or interactions with CAPTCHA-protected pages.
3. Form Automation: Automating repetitive tasks, such as filling out and submitting forms, often needs bypassing CAPTCHA to complete the workflow.

Prerequisites

Before we dive into the code, there are a few prerequisites you should have in place to follow along with this tutorial successfully:

Basic Understanding of JavaScript: This tutorial assumes you have a basic knowledge of JavaScript, including familiarity with concepts like variables, functions, and asynchronous programming.
Node.js and npm: We will be using Node.js, a JavaScript runtime, along with npm (Node Package Manager) to manage our project’s dependencies. If you don’t have Node.js installed, you can download it from the official Node.js website.
CapSolver API Key: To effectively solve reCAPTCHA challenges, you’ll need access to a service like CapSolver, which specializes in solving CAPTCHA challenges programmatically. Make sure you sign up and obtain an API key from CapSolver to integrate it into your solution.

Once you’ve met these prerequisites, you’re ready to set up your environment and start solving reCAPTCHA challenges with JavaScript and CapSolver.

Steps to Solve reCAPTCHA with JavaScript

Obtaining the Site Key

In the browser’s request logs, search for the request /recaptcha/api2/reload?k=6Le-wvkSAAAAAPBMRTvw0Q4Muexq9bi0DJwx_mJ-, where the value after k= is the Site Key we need. Or you can find all the paramters to solve recapctha through CapSolver extension
The URL is the address of the page that triggers the reCAPTCHA V2.

Install the requests library

pip install requests

Example code

import requests
import time
from DrissionPage import ChromiumPage

# Create an instance of ChromiumPage
page = ChromiumPage()# Access the example page that triggers reCAPTCHA
page.get("https://www.google.com/recaptcha/api2/demo")# TODO: Set your configuration
api_key = "your api key of capsolver"  # Your CapSolver API key
site_key = "6Le-wvkSAAAAAPBMRTvw0Q4Muexq9bi0DJwx_mJ-"  # Site key of your target site
site_url = "https://www.google.com/recaptcha/api2/demo"  # Page URL of your target sitedef capsolver():
    payload = {
        "clientKey": api_key,
        "task": {
            "type": 'ReCaptchaV2TaskProxyLess',
            "websiteKey": site_key,
            "websiteURL": site_url
        }
    }
    # Send a request to CapSolver to create a task
    res = requests.post("https://api.capsolver.com/createTask", json=payload)
    resp = res.json()
    task_id = resp.get("taskId")
    if not task_id:
        print("Failed to create task:", res.text)
        return
    print(f"Got taskId: {task_id} / Getting result...")    while True:
        time.sleep(3)  # Delay
        payload = {"clientKey": api_key, "taskId": task_id}
        # Query task results
        res = requests.post("https://api.capsolver.com/getTaskResult", json=payload)
        resp = res.json()
        status = resp.get("status")
        if status == "ready":
            return resp.get("solution", {}).get('gRecaptchaResponse')
        if status == "failed" or resp.get("errorId"):
            print("Solve failed! response:", res.text)
            returndef check():
    # Get the reCAPTCHA solution
    token = capsolver()
    # Set the reCAPTCHA response value
    page.run_js(f'document.getElementById("g-recaptcha-response").value="{token}"')
    # Call the success callback function
    page.run_js(f'onSuccess("{token}")')
    # Submit the form
    page.ele('x://input[@id="recaptcha-demo-submit"]').click()if __name__ == '__main__':
    check()

Explanation:

Obtaining the Site Key: Look for the request containing the k= parameter in the browser’s request logs, and extract the value following k= as the Site Key.
Set the configuration: Replace api_key, site_key, and site_url in the code with your actual values.
Execute the code: By calling the check() function, the code will automatically retrieve the reCAPTCHA solution and submit the form.

Make sure to comply with the terms of service and legal regulations of the websites you interact with.

Conclusion

Solving reCAPTCHA challenges programmatically with JavaScript offers a powerful solution for automating tasks that involve interacting with web services protected by CAPTCHA. By leveraging tools like Puppeteer and CapSolver, you can effectively bypass these challenges, streamline your workflows, and integrate automated solutions into your projects.

As reCAPTCHA continues to evolve, staying informed about its different versions and utilizing appropriate strategies becomes crucial. Whether you’re tackling web scraping, automated testing, or form automation, understanding how to manage reCAPTCHA efficiently can greatly enhance your productivity and accuracy.

Remember, while automation can significantly boost efficiency, it’s essential to respect the terms of service of the websites you engage with and ensure compliance with legal standards. With the right tools and knowledge, you can navigate the complexities of reCAPTCHA and focus on what truly matters in your development efforts.

Note on Compliance

Important: When engaging in web scraping, it’s crucial to adhere to legal and ethical guidelines. Always ensure that you have permission to scrape the target website, and respect the site’s robots.txt file and terms of service. CapSolver firmly opposes the misuse of our services for any non-compliant activities. Misuse of automated tools to bypass CAPTCHAs without proper authorization can lead to legal consequences. Make sure your scraping activities are compliant with all applicable laws and regulations to avoid potential issues.