How to solve and bypass captcha for free

This article explains how to build a free captcha solver in PHP using the Tesseract OCR engine and the tesseract_ocr wrapper.

Free text-based captcha solver in PHP using Tesseract OCR

This article explains how to build a minimal text free captcha solver in PHP using the Tesseract OCR engine and the thiagoalessio/tesseract_ocr wrapper.

1. Install dependencies

Tesseract OCR

On Linux:

sudo apt update
sudo apt install tesseract-ocr -y

On Windows: download from Tesseract Wiki and add tesseract.exe to your PATH.

PHP Wrapper

composer require thiagoalessio/tesseract_ocr

2. Minimal working script

<?php

require __DIR__ . '/vendor/autoload.php';

use thiagoalessio\TesseractOCR\TesseractOCR;

$ocr = new TesseractOCR('captcha.jpg');
$ocr->lang('eng');
$ocr->setOptions([
    'tessedit_char_whitelist' => 'ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789'
]);

$text = $ocr->run();
$cleaned = preg_replace('/[^A-Z0-9]/', '', strtoupper($text));

echo "Recognized text: $cleaned\n";

3. Optional: Image preprocessing

For low-quality images, preprocessing may improve OCR accuracy. You can use PHP GD for basic grayscale and contrast adjustments:

<?php

$im = imagecreatefromjpeg('captcha.jpg');
imagefilter($im, IMG_FILTER_GRAYSCALE);
imagefilter($im, IMG_FILTER_CONTRAST, -50);
imagejpeg($im, 'captcha_prepared.jpg');
imagedestroy($im);

Update the OCR input path to use 'captcha_prepared.jpg'.

4. Test captcha generation

You can generate a simple CAPTCHA image for testing using ImageMagick:

convert -size 150x60 xc:white -font Arial -pointsize 30 -fill black -draw "text 20,40 'AB12'" captcha.jpg

5. Issues

6. Final Code with Preprocessing

<?php

require __DIR__ . '/vendor/autoload.php';

use thiagoalessio\TesseractOCR\TesseractOCR;

// Step 1: Preprocess image
$source = 'captcha.jpg';
$prepared = 'captcha_prepared.jpg';

$im = imagecreatefromjpeg($source);
imagefilter($im, IMG_FILTER_GRAYSCALE);
imagefilter($im, IMG_FILTER_CONTRAST, -50);
imagejpeg($im, $prepared);
imagedestroy($im);

// Step 2: Run OCR
$ocr = new TesseractOCR($prepared);
$ocr->lang('eng');
$ocr->setOptions([
    'tessedit_char_whitelist' => 'ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789'
]);

$text = $ocr->run();
$cleaned = preg_replace('/[^A-Z0-9]/', '', strtoupper($text));

echo "Recognized text: $cleaned\n";

7. Limitations

This method only works on simple image-based CAPTCHAs with clear alphanumeric text and minimal distortion. It is not suitable for modern CAPTCHA systems that use:

• Obfuscation and heavy noise
• Dynamic rendering (canvas/webGL)
• Behavioral tracking (mouse movement, clicks)
• Interactive tasks (image classification, drag and drop)

Examples include:

• Google reCAPTCHA v2/v3
• hCaptcha
• Cloudflare Turnstile
• GeeTest

To handle such CAPTCHAs, you need third-party solving services with real-time support, such as 2Captcha captcha solver. These services use machine learning and human solvers to deliver reliable tokens and support complex flows via API.

If you want a working example using 2Captcha in PHP or via browser automation, check - PHP captcha solver.

While this example uses PHP, CAPTCHA solving can be automated in many other languages using the same tools:

Supported:

• PHP
• Java
• Python
• Ruby
• C#
• Go
• JavaScript