SOS Captcha — Privacy-First Spam Protection

Stop spam without collecting visitor data.

SOS Captcha protects your WordPress forms with an interactive slider challenge. Visitors drag a handle along a track to prove they are human. The plugin runs entirely on your own server — no tracking, no cookies, no external services.

Privacy by design

• No tracking pixels or analytics
• No cookies stored
• No data sent to external services
• GDPR, CCPA, and ePrivacy friendly
• All validation happens on your server

Visitor-friendly slider

• Touch-friendly interaction works on mobile
• Most visitors complete it in a few seconds
• Smooth animation on success

How the protection works

• Unique cryptographic tokens per session
• Random checkpoint positions (up to 8 in Free, 15 in Premium)
• Server-side timing validation
• Rate limiting (configurable, 60s default)
• Behavioral analysis (Premium)
• Honeypot fields and browser fingerprinting (Premium)

Form integrations

• Contact Form 7 (Free)
• WordPress Comments (Free)
• WPForms (Premium)
• Gravity Forms (Premium)
• Ninja Forms (Premium)
• WooCommerce checkout, registration & reviews (Premium)

Authentication form protection (Premium)

• WordPress login form (wp-login.php) — protect against brute-force attacks
• User registration form — prevent bot-generated accounts
• Lost-password form — block password-reset email spam

How it works

SOS presents a slider with randomly positioned checkpoints. Visitors slide a cursor along the track to activate each checkpoint in sequence. Each session generates unique cryptographic tokens with millions of possible combinations and server-side timing validation. Premium plans add behavioral analysis on top.

Free vs Premium

Free version includes:

• Unlimited forms and submissions
• Contact Form 7 integration
• WordPress comments protection
• Customizable appearance (colors, text)
• Up to 8 checkpoints per challenge
• Full GDPR compliance
• Community support

Premium features:

• WPForms, Gravity Forms, Ninja Forms integrations
• WooCommerce protection (checkout, registration, reviews)
• WordPress login, registration, and lost-password protection
• Advanced behavioral detection
• Browser fingerprinting
• Honeypot fields
• Local statistics dashboard (privacy-first, no data leaves your server)
• Priority email support
• White-label (remove badge)
• Up to 15 checkpoints per challenge

Upgrade to Premium — from €4.99/month or €47/year.

Technical Highlights

• Cryptographic security: Unique tokens per session with server-side validation
• No database bloat: Uses WordPress transients (auto-cleanup)
• Lightweight: Under 20KB total assets
• Performance: Cached responses, minimal server load
• Developer-friendly: Hooks and filters for customization
• Translation-ready: 10 languages included (EN, FR, DE, ES, IT, PT-BR, AR, JA, ZH, HI)

Compliance

• GDPR Article 25 (Privacy by Design)
• CCPA compliant (no personal data collection)
• ePrivacy Directive compliant (no cookies)

Support & Documentation

• Documentation at https://sos-captcha.com
• Community forum (Free)
• Email support (Premium)
• French and English support

Source Code

The plugin ZIP ships both the human-readable source (assets/challenge-slider.js, admin/js/sos-admin.js, assets/*.css, admin/css/*.css) and the minified production builds (.min.js, .min.css). WordPress loads the minified versions in production and the source versions when SCRIPT_DEBUG is enabled (define('SCRIPT_DEBUG', true) in wp-config.php).

Privacy Policy

SOS Captcha is designed with privacy at its core:

Data collection: None. We don’t collect, store, or transmit any personal data to external servers.

Cookies: None. The plugin sets no cookies.

External services: None. All processing happens on your WordPress server.

IP addresses: Not stored. Rate limiting uses transient hashes that auto-expire.

Statistics (Premium): Stored locally on your server only. Aggregated counters (blocked spam, form types) with no personally identifiable information.

Licensing (Premium only): When you activate a Premium license, your site URL and license key are sent to https://sos-captcha.com to validate the license. No user data is transmitted.

Hooks for Developers

• sos_before_validation — Modify validation parameters
• sos_challenge_created — React to new challenges
• sos_spam_blocked — Trigger actions when spam is blocked
• sos_should_show_badge — Control badge visibility