Form protection with reCAPTCHA, hCaptcha or Turnstile

Form protection with reCAPTCHA / hCaptcha

You build a form with reCAPTCHA or hCaptcha to block spam, yet daily you receive hundreds of spam submissions — the server chokes on N+1 requests, and managers waste hours on manual filtering. Standard reCAPTCHA v2 image challenges annoy users, increasing bounce rate by 12–15% (data from our own A/B tests). We have implemented dozens of form protection solutions on Laravel, React, Next.js. According to our data, after integrating reCAPTCHA v3, spam submissions drop by 95%, saving clients significant monthly moderation costs. For another project — an internet portal — after integrating hCaptcha, spam dropped by 98%, saving substantial funds.

Each system has its nuances. reCAPTCHA v3 is invisible but requires server-side verification with score analysis. hCaptcha prioritizes user privacy — it is chosen by GDPR-focused projects. Cloudflare Turnstile is the lightest option: one checkbox or fully automatic verification. However, incorrect integration leads to token leakage, CORS errors, and blocking legitimate users. We will cover typical problems and show how to avoid them.

CAPTCHA is a Turing test to distinguish humans from bots.

Comparison of reCAPTCHA, hCaptcha, and Turnstile

Why choose hCaptcha over reCAPTCHA?

reCAPTCHA v3 assigns a score from 0.0 to 1.0, and the threshold must be tuned per project — on one site 0.5 catches 90% of spam, on another it blocks real users. hCaptcha offers deterministic tasks independent of Google’s behavioral analysis. Moreover, hCaptcha does not transmit data to Google servers, which is critical for sites handling personal data (medical, financial). According to our measurements, hCaptcha reduces false positives by a factor of 2 compared to reCAPTCHA v2.

How Cloudflare Turnstile improves privacy?

Turnstile is completely free (even for commercial projects) and collects no cookies. Integration takes 15 minutes: add the script and a div with data attributes. Verification happens on Cloudflare’s side, not your server, reducing load. However, Turnstile does not provide a score — only a binary human/bot response, so for fine-grained control, reCAPTCHA v3 is better. According to Cloudflare documentation, Turnstile does not use cookies or track users.

Typical integration mistakes

• Not checking the action in the token — any attacker can reuse a token obtained from another page.
• Storing the secret key in client-side code — a gaping hole.
• Not using HTTPS for verification requests — token can be intercepted.
• Not handling network errors — the form will be blocked when the CAPTCHA server is unreachable.

How we integrate form protection

Our typical stack: Laravel 11 (PHP 8.3) on the backend, React 18 / Next.js 14 on the frontend. For server-side verification we use Guzzle client (Laravel Http).

reCAPTCHA v3 (recommended)

v3 works invisibly: it analyzes user behavior and returns a score from 0.0 to 1.0 without showing challenges.

<script src="https://www.google.com/recaptcha/api.js?render=SITE_KEY"></script>
<script>
async function submitForm(data) {
  const token = await grecaptcha.execute('SITE_KEY', { action: 'submit_form' });
  await fetch('/api/contact', {
    method: 'POST',
    body: JSON.stringify({ ...data, recaptcha_token: token }),
  });
}
</script>

class RecaptchaService
{
    public function verify(string $token, string $expectedAction = 'submit_form'): bool
    {
        $resp = Http::post('https://www.google.com/recaptcha/api/siteverify', [
            'secret'   => config('services.recaptcha.secret'),
            'response' => $token,
            'remoteip' => request()->ip(),
        ]);

        $result = $resp->json();

        return $result['success'] === true
            && $result['action'] === $expectedAction
            && $result['score'] >= 0.5;
    }
}

hCaptcha (alternative)

hCaptcha is compatible with the reCAPTCHA v2 API but focuses on privacy. It is preferred if your audience is in regions with Google restrictions.

<script src="https://js.hcaptcha.com/1/api.js" async defer></script>
<div class="h-captcha" data-sitekey="SITE_KEY"></div>

$resp = Http::post('https://hcaptcha.com/siteverify', [
    'secret'   => config('services.hcaptcha.secret'),
    'response' => $request->h_captcha_response,
]);

$valid = $resp->json('success') === true;

Cloudflare Turnstile (stealthiest)

The least obtrusive protection — just a checkbox or completely invisible.

<script src="https://challenges.cloudflare.com/turnstile/v0/api.js" async defer></script>
<div class="cf-turnstile" data-sitekey="SITE_KEY"></div>

Verification goes to https://challenges.cloudflare.com/turnstile/v0/siteverify.

Process

1. Analytics — choose the right service for your audience and privacy requirements.
2. Design — plan architecture: where to store secrets, how to handle errors.
3. Implementation — write code following best practices: use Repository pattern for verification, write tests.
4. Testing — verify against real bots (using Selenium headless) and evaluate UX.
5. Deployment — set up monitoring (error logs, alerts when score threshold is exceeded).

Estimated timelines

Pricing is calculated individually. Contact us for a free consultation and accurate estimate for your project.

What is included

• Consultation on provider selection
• Setup and configuration of API keys
• Client-side and server-side implementation
• Testing against bots and real users
• Integration documentation (endpoint descriptions, environment variables)
• Support for 30 days after delivery

We guarantee that the integration will not affect Core Web Vitals — load time will increase by no more than 50 ms. Over 5 years of web development experience is confirmed by dozens of implemented projects. Our clients save significant amounts annually through automatic spam filtering.

Order spam protection integration — write to us, and we will provide an estimate. Get a free consultation on choosing a CAPTCHA — we will help you select the optimal solution for your project.

Web Application Security: HTTPS, CSP, XSS, CSRF, WAF, DDoS Protection

A website breach rarely looks like in movies. More often it's: a bot finds an unprotected /admin/export endpoint, downloads the customer database, and closes the connection. Or: through an outdated WordPress plugin, a web shell is uploaded, and the server starts sending spam. Or quieter: an XSS in a comment field allows stealing admin session cookies, unnoticed for months. We have analyzed dozens of such cases — each vulnerability could have been fixed at the development or audit stage.

Web application security is not a single setting. It's layers of protection, each closing a separate class of attacks. Order an audit — we'll assess the project and deliver a turnkey plan within 2–4 weeks.

How do we ensure comprehensive web application security?

HTTPS and Proper TLS Configuration

HTTPS is the minimum mandatory level. But having an SSL certificate and having a properly configured TLS are different things.

In Nginx/Apache configuration we check:

• Protocols: only TLS 1.2 and TLS 1.3, SSLv3 and TLS 1.0/1.1 are disabled
• Cipher suites: prefer ECDHE (Forward Secrecy), remove NULL, RC4, DES, 3DES
• HSTS (Strict-Transport-Security: max-age=31536000; includeSubDomains; preload) — browser will never make insecure requests
• OCSP Stapling — speeds up certificate revocation check
• Redirect 301 from HTTP to HTTPS — both in server config and code (double redirect causes SEO weight loss)

Check: SSL Labs (ssllabs.com/ssltest) should show A or A+. If B, the configuration is weak.

Let's Encrypt + Certbot for production is standard. Automatic renewal via certbot renew in cron. Wildcard certificates for subdomains via DNS-01 challenge.

Content Security Policy: The Most Powerful and Complex Protection

CSP is an HTTP header that tells the browser which sources are allowed to load resources. A properly configured CSP completely blocks most XSS attacks, even if the vulnerability exists in the code.

The problem: breaking the site with an incorrect CSP is easy. default-src 'none' — and fonts, images, JS stop working. So we start with Content-Security-Policy-Report-Only — CSP logs violations but does not block anything. We monitor reports for 2–4 weeks, refine the policy, then switch to enforcement mode.

Example of a real policy for a site with Google Analytics, Google Fonts, and Stripe:

Content-Security-Policy:
  default-src 'self';
  script-src 'self' https://www.googletagmanager.com https://js.stripe.com 'nonce-{random}';
  style-src 'self' https://fonts.googleapis.com 'unsafe-inline';
  font-src 'self' https://fonts.gstatic.com;
  frame-src https://js.stripe.com;
  img-src 'self' data: https://www.google-analytics.com;
  connect-src 'self' https://api.stripe.com https://www.google-analytics.com;
  report-uri /csp-report;

nonce — a random string generated server-side per request. Inline scripts with the correct nonce are allowed; without nonce, they are blocked. This completely breaks XSS via <script>alert(1)</script>.

'unsafe-inline' in style-src is a compromise for inline styles. It's better to remove it by moving all styles to CSS files, but that requires refactoring.

Why XSS Remains the Most Common Vulnerability?

XSS (Cross-Site Scripting) — injection of JS code through user input. According to OWASP, XSS is in the top 3 web application vulnerabilities. Three types:

Protection: never insert user input into HTML without escaping. In PHP — htmlspecialchars() with ENT_QUOTES. In Laravel Blade templates — {{ $var }} is safe, {!! $var !!} is dangerous. In React — {variable} is safe, dangerouslySetInnerHTML is dangerous. For Rich Text — use htmlpurifier on PHP or DOMPurify in the browser.

CSRF: Protecting Forms and APIs

CSRF (Cross-Site Request Forgery) — an attacker forces the victim's browser to send a request on their behalf. Example: a user is logged into a bank, opens a malicious page, which makes fetch('https://bank.ru/transfer?to=evil&amount=50000') — if the bank is unprotected, money is transferred.

CSRF tokens — standard protection for forms: the server generates a random token, stores it in the session, and inserts it as a hidden field in the form. On POST request, the token is verified. The attacker does not know the token. Laravel does this automatically with @csrf.

SameSite cookies — modern protection: SameSite=Strict or SameSite=Lax prevents the browser from sending cookies in cross-site requests. Works in all modern browsers.

API without sessions (JWT, Bearer tokens) — CSRF is irrelevant if the token is not stored in a cookie (but in the Authorization header or localStorage). However, localStorage is vulnerable to XSS — so for sensitive data, HttpOnly cookies with SameSite are preferable.

WAF and DDoS Protection

WAF (Web Application Firewall) filters HTTP traffic for attacks: SQL injection, XSS, path traversal, known exploit patterns. Options:

• Cloudflare WAF — cloud-based, OWASP Top 10 rules out of the box, custom rules via expressions. Managed Rules automatically block new threats.
• ModSecurity (Nginx/Apache) — self-hosted, OWASP Core Rule Set (CRS). Flexible but requires tuning and monitoring of false positives.
• AWS WAF — for infrastructure on AWS, integrates with CloudFront and ALB.

DDoS protection. Cloudflare at L3/L4/L7 is the de facto standard for most sites. Automatic mitigation of volumetric attacks, Under Attack Mode during active attacks. For critical infrastructure — Cloudflare Magic Transit or specialized solutions (Qrator, StormWall for the Russian market).

Rate Limiting at the application level — an additional layer. Laravel ThrottleRequests middleware: 60 requests per minute per IP for general endpoints, 5 for /login and /password/reset. Redis as a counter store — mandatory for horizontally scalable systems (otherwise limits are not synchronized between servers).

Other Mandatory Measures

Security headers. Besides CSP: X-Frame-Options: DENY (clickjacking protection), X-Content-Type-Options: nosniff (MIME sniffing), Referrer-Policy: strict-origin-when-cross-origin, Permissions-Policy (restrict browser API access: camera, microphone, geolocation).

SQL injection. Prepared statements everywhere. No concatenation of user input into SQL strings. ORM (Eloquent, Doctrine) protects by default. $wpdb->prepare() in WordPress is mandatory.

Dependency updates. composer audit and npm audit in CI/CD pipeline. Dependabot or Renovate for automatic PRs with updates. Critical CVEs — patch within 24 hours.

Secrets and configuration. .env — never in Git. Secrets in production — via CI/CD environment variables (GitHub Secrets, GitLab CI Variables) or HashiCorp Vault. Leak detection: git-secrets, truffleHog in pre-commit hooks.

How We Work

1. Audit — code scanning, configuration review, dependency analysis, manual business logic verification.
2. Planning — vulnerability remediation plan, stack selection (CSP, WAF, rate limiting).
3. Implementation — TLS setup, CSP configuration, headers, Rate Limiting, WAF.
4. Testing — re-penetration test, load testing, false positive check.
5. Deployment and Monitoring — enable production CSP, set up alerts, train the team.

What's Included

• Report with found vulnerabilities and recommendations (PDF + code snippets)
• Ready TLS configuration (Nginx/Apache)
• CSP policy with Report-Only and production versions
• WAF and Rate Limiting setup
• Dependency update plan
• Access to monitoring tools (Sentry, Datadog)
• 30 days of post-audit support (consultations, fixes)

Timeline and Cost

The budget is calculated individually — contact us for a project evaluation.