Automated Form Submission with CAPTCHA Handling

Automate form submissions that include CAPTCHA challenges using Selenium and CaptchaAI.

The Challenge

Web forms protected by CAPTCHAs block automation. Whether you're testing contact forms, submitting applications, or running QA workflows, you need to solve the CAPTCHA before the form will accept your submission.

Architecture

┌────────────┐     ┌──────────────┐     ┌────────────┐     ┌──────────────┐
│ Load Form  │────▶│ Fill Fields  │────▶│ Detect &   │────▶│ Submit Form  │
│ (Selenium) │     │              │     │ Solve      │     │              │
│            │     │              │     │ CAPTCHA    │     │              │
└────────────┘     └──────────────┘     └────────────┘     └──────────────┘

Core Components

CAPTCHA Solver

import time
import requests


class FormCaptchaSolver:
    BASE = "https://ocr.captchaai.com"

    def __init__(self, api_key):
        self.api_key = api_key

    def solve(self, params, initial_wait=10):
        params["key"] = self.api_key
        params["json"] = 1
        resp = requests.post(f"{self.BASE}/in.php", data=params).json()
        if resp["status"] != 1:
            raise Exception(f"Submit error: {resp['request']}")

        task_id = resp["request"]
        time.sleep(initial_wait)

        for _ in range(60):
            result = requests.get(
                f"{self.BASE}/res.php",
                params={"key": self.api_key, "action": "get", "id": task_id, "json": 1},
            ).json()
            if result["request"] == "CAPCHA_NOT_READY":
                time.sleep(5)
                continue
            if result["status"] == 1:
                return result["request"]
            raise Exception(f"Solve error: {result['request']}")
        raise TimeoutError("CAPTCHA solve timed out")

CAPTCHA Detector

import re
from selenium.webdriver.common.by import By


class CaptchaDetector:
    def __init__(self, driver):
        self.driver = driver

    def detect(self):
        """Detect CAPTCHA type on current page."""
        html = self.driver.page_source

        # Turnstile
        turnstile = self.driver.find_elements(By.CSS_SELECTOR, ".cf-turnstile, [data-sitekey]")
        for el in turnstile:
            if "cf-turnstile" in (el.get_attribute("class") or ""):
                return "turnstile", el.get_attribute("data-sitekey")

        # reCAPTCHA
        recaptcha = self.driver.find_elements(By.CSS_SELECTOR, "[data-sitekey]")
        if recaptcha:
            sitekey = recaptcha[0].get_attribute("data-sitekey")
            if "recaptcha" in html.lower():
                return "recaptcha_v2", sitekey

        # Image CAPTCHA
        img = self.driver.find_elements(By.CSS_SELECTOR, "img[src*='captcha'], img.captcha")
        if img:
            return "image", img[0].get_attribute("src")

        return "none", None

Form Automator

import base64
import requests as req
from selenium import webdriver
from selenium.webdriver.common.by import By
from selenium.webdriver.support.ui import WebDriverWait
from selenium.webdriver.support import expected_conditions as EC


class FormAutomator:
    def __init__(self, api_key):
        self.solver = FormCaptchaSolver(api_key)
        self.driver = webdriver.Chrome()
        self.detector = CaptchaDetector(self.driver)

    def fill_field(self, selector, value):
        field = WebDriverWait(self.driver, 10).until(
            EC.presence_of_element_located((By.CSS_SELECTOR, selector))
        )
        field.clear()
        field.send_keys(value)

    def select_option(self, selector, value):
        from selenium.webdriver.support.ui import Select
        select = Select(self.driver.find_element(By.CSS_SELECTOR, selector))
        select.select_by_value(value)

    def solve_captcha(self):
        captcha_type, data = self.detector.detect()
        page_url = self.driver.current_url

        if captcha_type == "recaptcha_v2":
            token = self.solver.solve({
                "method": "userrecaptcha",
                "googlekey": data,
                "pageurl": page_url,
            })
            self.driver.execute_script(
                f'document.querySelector("[name=g-recaptcha-response]").value = "{token}";'
            )
            return True

        if captcha_type == "turnstile":
            token = self.solver.solve({
                "method": "turnstile",
                "sitekey": data,
                "pageurl": page_url,
            })
            self.driver.execute_script(
                f'document.querySelector("[name=cf-turnstile-response]").value = "{token}";'
            )
            return True

        if captcha_type == "image":
            img_data = req.get(data).content
            img_b64 = base64.b64encode(img_data).decode()
            text = self.solver.solve({"method": "base64", "body": img_b64})
            captcha_input = self.driver.find_element(
                By.CSS_SELECTOR, "input[name*='captcha']"
            )
            captcha_input.clear()
            captcha_input.send_keys(text)
            return True

        return False  # No CAPTCHA detected

    def submit_form(self, url, fields, submit_selector="button[type='submit']"):
        """
        fields: list of (selector, value) tuples
        """
        self.driver.get(url)

        for selector, value in fields:
            self.fill_field(selector, value)

        self.solve_captcha()

        submit = self.driver.find_element(By.CSS_SELECTOR, submit_selector)
        submit.click()

        return self.driver.current_url

    def close(self):
        self.driver.quit()

Complete Example: Contact Form

automator = FormAutomator("YOUR_API_KEY")

try:
    result_url = automator.submit_form(
        url="https://example.com/contact",
        fields=[
            ("#name", "John Doe"),
            ("#email", "john@example.com"),
            ("#subject", "Sales inquiry"),
            ("#message", "I'd like to learn more about your services."),
        ],
        submit_selector="#submit-btn",
    )
    print(f"Form submitted. Redirected to: {result_url}")
finally:
    automator.close()

Handling Multiple Form Types

result = automator.submit_form(
    url="https://example.com/login",
    fields=[
        ("#username", "testuser"),
        ("#password", "testpass123"),
    ],
    submit_selector="#login-btn",
)

Registration Form

result = automator.submit_form(
    url="https://example.com/register",
    fields=[
        ("#first-name", "Jane"),
        ("#last-name", "Smith"),
        ("#email", "jane@example.com"),
        ("#password", "SecurePass!123"),
        ("#confirm-password", "SecurePass!123"),
    ],
    submit_selector="#register-btn",
)

result = automator.submit_form(
    url="https://example.com/search",
    fields=[
        ("#query", "python developer"),
        ("#location", "San Francisco"),
    ],
    submit_selector="#search-btn",
)

Troubleshooting

Issue	Cause	Fix
Token rejected	Token expired before submission	Solve CAPTCHA last, submit immediately
Field not found	Dynamic page loading	Add explicit waits
Wrong CAPTCHA type detected	Multiple CAPTCHA elements	Check detection order
Form reloads after submit	Server-side validation failed	Check all required fields
reCAPTCHA callback not triggered	Need to call callback function	Use `grecaptcha.execute()` after injection

FAQ

Can I submit forms without a browser?

For reCAPTCHA and Turnstile, you can solve CAPTCHAs without a browser and submit via HTTP POST. But if the form uses JavaScript validation, a browser is needed.