CAPTCHA systems are designed to look for patterns that distinguish bots from humans. By injecting randomness and human-like behavior into your scrapers actions, you make it much harder for these systems to tell the difference, reducing the chances of being blocked.
- Understanding CAPTCHA and its uses
- What triggers a CAPTCHA
- Why might you want to bypass CAPTCHAs?
- How to bypass CAPTCHA using proxies
- How to bypass CAPTCHAs using headless browsers
- How to avoid CAPTCHAs by keeping consistent metadata
- How SOAX helps you to bypass CAPTCHA
Understanding CAPTCHA and its uses
CAPTCHA is an acronym for Completely Automated Public Turing test to tell Computers and Humans Apart. As the name suggests, a CAPTCHA’s primary purpose is to differentiate between traffic from humans and traffic from automated bots. They do this by presenting challenge-response tests (for example, distorted text, or image recognition) that are easy for humans to solve, but difficult for machines.
What is CAPTCHA and how does it work?
Websites use CAPTCHAs to protect website logins, prevent spam, safeguard online forms from manipulation, and even ensure fair ticket prices. While CAPTCHAs have an important role in maintaining the integrity of some websites, they pose a problem for people who want to scrape the web using automated data extraction processes.
CAPTCHAs are one of the more primitive bot detection solutions that websites use. Newer bot detection solutions (like Cloudflare, DataDome, and Akamai) go beyond simple challenge-response tests and instead use a combination of techniques to identify and mitigate bot activity.
What triggers a CAPTCHA?
You can trigger a CAPTCHA by exhibiting behaviors that do not match normal human interaction patterns. This will lead some websites to believe your browsing behavior is bot traffic rather than human traffic. These triggers include:
- Request rate and volume: For example, sending an excessive number of requests in a short period, or consistently making a large number of requests from a single IP address.
- Unusual patterns and anomalies: For example, repeatedly performing the same action (such as clicking on the same link multiple times) or interacting with elements in an unusual order.
- Suspicious metadata: For example, if your browser has missing or inconsistent metadata, or has headers that are commonly associated with bots.
- External factors: For example, if your IP address has been flagged for suspicious activity in the past.
Websites analyze your IP reputation, request history, and even your mouse movements and keystrokes to decide whether to serve you with a human verification test.
Sometimes, you might encounter multiple CAPTCHAs in a row. This might happen because you have failed a previous CAPTCHA, or if you’ve triggered more than one of a website’s bot detection measures.
Reasons to bypass CAPTCHA
Web scraping relies on automated tools to extract large amounts of data from websites, and CAPTCHAs can significantly hinder this process. For example, researchers and analysts often need to scrape public data for various purposes such as market analysis, academic studies, or price comparisons. Bypassing CAPTCHAs is essential if you want to efficiently gather the information you need.
How to bypass CAPTCHA using proxies
If you’ve ever used a VPN or a free public proxy to browse the web, you may have experienced a frustrating loop of CAPTCHA challenges that prevents you from accessing the website you are trying to visit – each time you solve a CAPTCHA challenge, another appears in a seemingly endless cycle.
This happens because websites use your IP address to track your activity, and free proxies and VPNs have IP addresses that many people share simultaneously. When a website sees too many requests coming from the same IP address in a short period, they may suspect the requests are coming from a bot and serve a CAPTCHA.
As a result, free proxies and VPNs have a very low success rate for web scraping. For effective data extraction, you need to use premium, ethically sourced proxies with large pools of trustworthy IP addresses.
Bypassing CAPTCHA with residential and mobile proxies
Routing your requests through residential IP addresses (from real residential properties) helps your automated script blend in with regular traffic and significantly reduces the likelihood of triggering CAPTCHAs. By rotating through different residential IP addresses, you make it harder for your target websites to identify your scraper as a bot. You can achieve similar results with mobile proxies, which give you the IP address of a real mobile device.
You can configure your scraper to use proxies – most scraping tools have built-in support for proxies. Ensure that your scraper rotates through different IP addresses with each request. Some proxy providers (like SOAX) offer automatic rotation features. You should also choose a proxy provider that has a large pool of proxies. The more IPs you have, the less likely it is that your target websites will detect your scraper.
How to bypass CAPTCHAs using headless browsers
Unlike regular web browsers, headless browsers don’t display any visual interface (which is why they’re called “headless”), but they can still navigate web pages, interact with elements, and execute JavaScript code. Headless browsers are fully scriptable, which means you can control their every move through code. As a result, they are able to mimic human-like browsing, making them less likely to trigger CAPTCHAs.
You can use commands to tell a headless browser where to go and what to do. For example, page.goto('https://example.com') navigates to a URL, while page.click('button[type="submit"]') clicks on a submit button.
You can also programmatically move the mouse cursor around the screen to simulate clicks and hovers, and even generate random movements to make it appear more natural. This makes it less likely for CAPTCHAs that track your mouse movements to determine if you are human – like reCAPTCHA v2's "I'm not a robot" checkbox – to spot your automated browsing.
You can also use headless browsers to simulate typing into text fields, including intentional typos or delays between keystrokes to replicate human-like behavior, and introduce random delays between actions to avoid the robotic consistency that often triggers CAPTCHAs.
Human behavior synthesizers
Going beyond basic automation, human behavior synthesizers add another layer of realism to your headless browser. These tools simulate the nuances of human browsing behavior, which makes your bot almost indistinguishable from a real user.
- Vary mouse movements: Instead of moving the cursor in straight lines or at constant speeds, the synthesizer introduces subtle curves, accelerations, and decelerations, to mimic the way real humans move a mouse.
- Simulate keystrokes: Typing speed, pauses between words, and even typos can be replicated to create a more convincing human-like typing pattern.
- Randomize clicks: Clicking behavior, including the time between clicks and the slight variations in click coordinates, can be randomized to further enhance the illusion of human interaction.
By incorporating these subtle behaviors into your headless browser, you can significantly reduce the risk of advanced CAPTCHA systems that analyze user interactions identifying your scraper as a bot.
How to avoid CAPTCHAs by keeping consistent metadata
Every time you visit a website, your browser sends metadata about you and your device (for example, the device you’re using, your time zone, and even the fonts you have installed) to the website’s server. Websites use this metadata to deliver a personalized experience to their visitors (such as displaying content in your preferred language and currency based on your language settings and location information), but they can also use it to detect and block automated bots.
Websites use this information to trigger CAPTCHA tests or outright block traffic, based on:
- Unusual patterns: Bots often have predictable patterns in their metadata. For example, they might make requests much faster than a human could.
- Missing or inconsistent information: Some bots have incomplete or inconsistent metadata. For example, they might be missing information about their operating system or have a timezone that doesn’t match their IP address location.
- Known bot signatures: Websites can compare your metadata with known signatures of common bots or scraping tools. For example, how a bot executes JavaScript code can be different from how a real browser would handle it.
Ensuring the information your scraper sends to websites remains the same across all requests helps your scraper to appear as a single, regular user. This makes your scraper less likely to trigger CAPTCHAs.
You can maintain consistent metadata through:
- User agent management
- Timezone control
- Language and Accept Headers
- Browser fingerprinting management
- Leak prevention
User agent management
- Hardcode a specific user agent string into your scraping script (this makes sure you send the same user agent with every request).
- User agent libraries are available in different programming languages (e.g. fake_useragent in Python) that provide a list of common user agents. You can randomly select one for each request.
- Some scraping tools allow you to easily customize HTTP headers, including the User-Agent.
Timezone control
- Make sure your operating system’s timezone matches the location you want your scraper to appear from.
- Many programming languages have libraries (e.g. pytz in Python) that allow you to programmatically set the time zone for your scraper.
- Some proxy providers allow you to set the time zone of the requests they forward via their proxy servers, which makes it easier to maintain consistency.
Language and accept headers
- Most libraries for making HTTP requests allow you to set custom headers. Make sure you include the Accept-Language and Accept headers with appropriate values.
- Some scraping frameworks provide higher-level abstractions for managing headers, making it easier to set and maintain them.
Leak prevention
- Even headless browsers can have unique fingerprints based on their settings and configuration. You can randomize or hide your browser fingerprint, making it harder for websites to track your scraper across different settings.
- Your scraper’s TLS configuration can also be used to identify it. Some programming languages offer libraries specifically designed for manipulating TLS configurations. For example, in Python, you could use the ssl module to customize the SSL context for your requests.
- Websites can use TCP/IP fingerprinting to identify specific software of devices. IP rotation and randomizing your TCP settings allows you to obscure your scraper’s TCP/IP fingerprint.
- WebRTC (Web Real-Time Communication) can potentially leak your real IP address, even if you're using a proxy. Disable WebRTC in your scraper and be mindful of potential DNS leaks that could reveal your true location.
How SOAX helps you to bypass CAPTCHA
SOAX has a number of tools designed to help you avoid bot detection when web scraping, allowing you to focus on collecting the data you need:
- With more than 200M proxies in 195 counties and automatic rotation, SOAX proxies can route your requests through residential and mobile IP addresses to make your scraping activity appear like regular user traffic and reduce the likelihood of triggering CAPTCHAs. All our proxies are exclusive - we don’t share or resell our IPs with anyone else, which makes them less likely to be flagged as bot traffic.
- Our scraper APIs are tailored to specific platforms like Google, Amazon, and social media networks. They handle the complexities of web scraping, including CAPTCHA challenges, for you. With built-in CAPTCHA-solving capabilities, you can effortlessly extract data in a structured format, ready for integration into your projects.
- Web Unblocker is a powerful tool that acts as an intermediary between your scraper and target websites. It intelligently mimics human behaviour, manages CAPTCHA challenges, retries failed requests, and switches IPs to ensure uninterrupted scraping. By replacing your current proxy with the Web Unblocker's API, you can unlock access to data without the hassle of manual CAPTCHA solving.
With SOAX, you can bypass CAPTCHAs effectively, optimize your scraping process, and gather the data you need.
