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

Error	Cause	Solution
`tesseract command not found`	Tesseract not installed or not in PATH	Install Tesseract and add it to system PATH
Empty OCR result	Low image quality	Apply grayscale, contrast, resize
File not found	Wrong or missing file path	Check if the image exists and is accessible

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: