'providers' => [
        // ...
        'Mews\Captcha\CaptchaServiceProvider',
    ]

    'providers' => [
        // ...
        Mews\Captcha\CaptchaServiceProvider::class,
    ]

    'aliases' => [
        // ...
        'Captcha' => 'Mews\Captcha\Facades\Captcha',
    ]

    'aliases' => [
        // ...
        'Captcha' => Mews\Captcha\Facades\Captcha::class,
    ]

return [
    'default'   => [
        'length'    => 5,
        'width'     => 120,
        'height'    => 36,
        'quality'   => 90,
        'math'      => true,  //Enable Math Captcha
        'expire'    => 60,    //Stateless/API captcha expiration
    ],
    // ...
];

    // [your site path]/Http/routes.php
    Route::any('captcha-test', function() {
        if (request()->getMethod() == 'POST') {
            $rules = ['captcha' => 'required|captcha'];
            $validator = validator()->make(request()->all(), $rules);
            if ($validator->fails()) {
                echo '<p style="color: #ff0000;">Incorrect!</p>';
            } else {
                echo '<p style="color: #00ff30;">Matched :)</p>';
            }
        }
    
        $form = '<form method="post" action="captcha-test">';
        $form .= '<input type="hidden" name="_token" value="' . csrf_token() . '">';
        $form .= '<p>' . captcha_img() . '</p>';
        $form .= '<p><input type="text" name="captcha"></p>';
        $form .= '<p><button type="submit" name="check">Check</button></p>';
        $form .= '</form>';
        return $form;
    });

    //key is the one that you got from json response
    // fix validator
    // $rules = ['captcha' => 'required|captcha_api:'. request('key')];
    $rules = ['captcha' => 'required|captcha_api:'. request('key') . ',math'];
    $validator = validator()->make(request()->all(), $rules);
    if ($validator->fails()) {
        return response()->json([
            'message' => 'invalid captcha',
        ]);

    } else {
        //do the job
    }

captcha();

Captcha::create();

captcha_src();

captcha_img();

Captcha::img();

captcha_img('flat');

Captcha::img('inverse');