What is a CAPTCHA?

CAPTCHAs are designed to test whether a user is human or engaging in some form of bot activity. The acronym stands for “Completely Automated Public Turing test to tell Computers and Humans Apart”. You might find yourself given a CAPTCHA on login or if you’ve failed to submit an entry to a website too many times.

Why are CAPTCHAs used?

As annoying as they can be to solve, CAPTCHA systems are used as a primary defense against automation and bots. They are frequently placed in locations where friction could deter an automation flow. Ideally, a CAPTCHA system would stop the automation altogether; otherwise, it would at least slow the activity down. These systems protect specific points on a site or app and can prevent bot logins, spam sign-ups, checkouts, and various other places. These systems should be challenging but at least solvable by humans and not by bots.

What Types of CAPTCHAs are there?

Each system varies in complexity, friction, and the time it takes to solve. It is often seen that the higher the protection, the more complex the CAPTCHA is. They can also be seen to scale, depending on the level of threat the site detects.

There are a few ways CAPTCHA systems are presented:

• Distorted text, where the solution is to decipher and input.
• Matching images with similar, such as “click all the tiles that contain a bus”.
• Rotate the image so that it matches that of the example
• Select all odd photos and compare them to the example provided here.
• A simple tick box to “confirm you are not a bot”.
• Slide the image to a specific location (occasionally, you’ll even be told how accurate you were to everyone else who solved it!)

Here’s an example:

Failing these could lead to rejection of your request or a loop of multiple puzzles being issued until the system is satisfied you’re a human and not a bot.

reCAPTCHA

reCAPTCHA is a free service offered by Google that replaces traditional CAPTCHAs. It is a more advanced system, serving users puzzles that bots or scripts should have a harder time-solving. This is because the examples given to users from the reCAPTCHA system are taken from real-world examples, such as textbooks, old newspapers, real-world locations, and photos of actual animals. ReCAPTCHA v3 was released in 2018 and is currently the latest version. It uses a JavaScript API to return a score between 0 and 1 for every request to a particular page without interrupting the user. A score of 0 is likely a bot, whereas a score of 1 is almost certainly a human.

As threats increase, so does Google's commitment to expanding the functionality and challenge of reCAPTCHA- even going as far as to present invisible challenges. Invisible CAPTCHAs are designed to run in the background by checking user behavior without interrupting the user experience. They assess subtle cues like mouse movements or time spent on a page, allowing genuine users to pass through while flagging suspicious activity for further verification. If a user fails an invisible CAPTCHA challenge, they can be given a physical challenge like a tick or swipe box.

What Triggers a CAPTCHA?

There’s a few ways CAPTCHA, even being human, is sometimes not enough to avoid them. Often, these systems are triggered by someone or something behaving in unexpected and usual patterns. For example, you can trigger a CAPTCHA by repeatedly failing a login or attempting to submit a form from the exact location too quickly.

We all know how annoying it can be to complete a CAPTCHA, let alone a string of them. Sometimes, human activities can set the system off; we all make mistakes, but these can be interpreted as suspicious. Some of the signals that might trigger a CAPTCHA are:

Sending too many requests: sending an excessive amount of requests in a short space of time (more than what would be classed as “humanly” possible) or from the same IP address. Unusual activity: browsing or acting in ways that might not be considered “normal” or human. Accessing from an unusual location: if you’re expected to be logging in from a device or a location frequently accessed but suddenly appear halfway around the world on an unknown device.

Sometimes, you might be served multiple CAPTCHAs in a row. This can happen because you have failed a previous CAPTCHA or if you’ve triggered more than one of a website’s bot detection measures. Websites will check factors such as your IP reputation, browsing history, and even your mouse movements and keystrokes to determine if a human verification test is necessary.

Why Bypass CAPTCHA?

CAPTCHAs can be frustrating, especially when you're the human and still getting caught in their web of challenges. So why would someone want to bypass them? First, they can be a time-consuming interruption, especially if you're dealing with multiple challenges in a row. For businesses, frequent CAPTCHA challenges can slow down workflows, block legitimate traffic, or even discourage customers. In some cases, users may need to bypass CAPTCHAs to access restricted content quickly, especially if the system mistakenly flags their activity as suspicious. While CAPTCHAs serve an essential purpose in preventing bots and abuse, they can sometimes hinder genuine user experiences.

Using Proxies to Bypass CAPTCHAS

Luckily, there’s a solution to every problem. In some cases, you can use proxies to get around CAPTCHA challenges. Proxies can help prevent challenges by rotating the IP addresses if you're automating or scripting. Not only is this best practice when web scraping, but rotating the IP addresses from which your requests come means you’re less likely to be flagged as suspicious.

A caveat to this, though: use the right proxy type. Not all proxies will pass; it's about picking the right tool for the job. If you’re using proxies and are still failing the challenge, it’s time to consider using another proxy or type of proxy. Some IP addresses may have been previously flagged or used on the site, which can spring the CAPTCHA challenge. Using a higher-quality proxy is likely a good idea if you know a site has particularly difficult and stringent anti-bot measures. The good news is that Rampage provides access to 10 residential proxy providers all under the same dashboard, so long gone are the days of needing to log into all the different provider's dashboards.

Using the right proxy extends to the type of proxy you use. For example, a mobile proxy such as Rampage Mobile may be a good choice for scraping apps. Mobile proxies can help you appear as if your activities are coming from a legitimate mobile user and device, which can help you blend in and pass without challenge.

By rotating through different IP addresses, you make it harder for your target websites to identify the activities from your script or scraper as a bot, avoiding potential challenges. Remember, the more IPs you have available to you, the less likely you are to get caught. All the residential and mobile providers on the Rampage dashboard allow for custom rotation or even rotation per request, expanding your capabilities to scrape or automate un-detected.

Using Headless Browsers to Bypass CAPTCHAS

Headless browsers operate without a browser window opening (hence the “headless” name), but they can still load web pages, interact with elements, and run JavaScript just like a regular browser. The key difference is that headless browsers are fully programmable, allowing you to control their actions through code. This makes them capable of simulating human-like browsing behavior, reducing the chances of triggering CAPTCHAs. We touched on this in other posts where we discussed web scraping with Selenium for example.

With headless browsers, you can control every action through specific commands in the code, guiding the browser on where to go and what tasks to do. For example, a simple command like page.goto('https://example.com') directs the browser to a particular URL, just as a user would type it into their address bar. Similarly, commands such as page.click('button[type="submit"]') will let you interact with page elements, like clicking a submit button. You can also use additional commands to fill out forms, scroll through pages, or even capture screenshots. Programs like Selenium or Puppeteer can instruct the headless browser to move the mouse cursor around the screen, simulating clicking and hovering and even introducing human-like movements to make it seem more natural.

It’s worth noting that some advanced anti-bot solutions are growing more aware of headless browsers and their methods, learning to detect and block. Services such as Cloudflare are known to do this.

Conclusion

CAPTCHAs are a crucial website defense, but they can be frustrating obstacles when you're a legitimate user or need to automate tasks. Understanding how they work and what triggers them is key to avoiding unnecessary challenges. Whether you're using proxies to rotate IPs or headless browsers to simulate human behavior, there are ways to navigate around CAPTCHAs while staying within ethical boundaries. As web scraping and automations becomes an even bigger market, anti-bot technology evolves. This means it's essential to stay updated on best practices and adapt your strategies accordingly.