Next-Gen Captcha
and Spam Protection
gptBuster is an advanced security platform that defends against bots and automated attacks without compromising user experience. It intelligently adapts to emerging threats, blending state-of-the-art detection with smooth verification to protect your digital assets and services.
Sentinel works invisibly in the background, utilizing machine learning and behavioral analysis to stop malicious activity. Whether securing user accounts, web forms, or API endpoints, it delivers military-grade protection while maintaining a seamless and accessible journey for legitimate users.

gptBuster is a self-hosted solution that ensures compliance with data protection and accessibility regulations worldwide.
Compliant with the General Data Protection Regulation.
Compliant with the Health Insurance Portability and Accountability Act.
Compliant with the California Consumer Privacy Act.
Compliant with the Canadian Consumer Privacy Protection Act.
Compliant with the Brazilian General Data Protection Law.
Compliant with India’s Digital Personal Data Protection Act.
Compliant with the Personal Information Protection Law of the People’s Republic of China.
gptBuster delivers automated, adaptive spam protection that dynamically responds to emerging threats.
Frictionless Verification
The system defaults to a Proof-of-Work (PoW) verification method, eliminating visual puzzles or disruptive challenges. This approach balances security with accessibility, offering an unobtrusive solution suitable for most users.
Code Challenge
For cases flagged as high-risk, the protection escalates to a secure code challenge. This includes an audio component, ensuring adherence to accessibility regulations like EAA and WCAG without compromising security.
* This is a demonstration showing only the user interface without full functionality.
gptBuster adapts to your language — with multilingual audio challenges, automatic translations, and RTL support, gptBuster delivers a seamless experience in 48+ languages for everyone.
Self-hosted, machine learning-powered defense against spam, bots, and automated attacks.
Block fake sign-ups and bot-created accounts with challenge-based verification.
Defend against credential stuffing and brute-force attacks on logins.
Stop spam in contact forms, surveys, and submissions without hurting user experience.
Filter spam in discussions and forums, reducing moderation work.
Block malicious bot traffic across web services and APIs to stop data scraping, service overload, and unauthorized access.
Keep spam and phishing attempts out of your email ingress.
gptBuster is packed with security features that help you protect your apps and services.
Adjusts difficulty based on user behavior to block bots effectively.
Analyzes and categorizes text inputs for malicious content.
Uses machine learning datasets to improve spam detection.
Identifies and blocks automated bots, crawlers and AI agents.
Flags requests from proxy servers or TOR networks.
Validates email addresses to reduce fake sign-ups.
Prevents abuse by limiting requests from a single source.
Checks IPs against known threat databases.
Restricts access based on geographic location of IP addresses.
Identifies and filters content based on detected languages.
Secures form submissions against spam and automated attacks.
Protect any URL with a verification page before redirecting users to the destination.
gptBuster provides enterprise-grade anti-spam protection for businesses and government organizations that require stringent compliance with global regulations, including data protection standards and the European Accessibility Act (EAA). Designed for security-conscious enterprises, GPTBUSTER ensures robust spam prevention while meeting the highest standards of privacy and accessibility.
gptBuster is a self-hosted solution with straightforward integration. A 30-day trial begins automatically upon installation.
Migration guides:
Examples
See example setups of GPTBUSTER with different front-end frameworks:
Official Libraries
gptBuster's TypeScript library runs everywhere! Whether it’s modern browsers, Node.js, Bun, Deno, or any WinterCG-compatible runtime.
Plugins
Visit the Integrations documentation for more community-developed libraries and plugins.
Robust Spam Protection and Privacy
GPTBUSTER offers a powerful, self-hosted alternative to traditional CAPTCHAs, putting privacy and transparency first. As an open-source solution, it gives you full control over your spam protection system, eliminating reliance on third-party services that may track user data.
Unlike other options, gptBuster is fully customizable, allowing you to tailor the challenge mechanism to your specific needs while ensuring GDPR compliance. Its lightweight design ensures fast, frictionless verification for real users while effectively blocking bots—all without compromising user privacy.
Stop Spam Without Compromising Privacy
GPTBUSTER - The accessible, privacy-first alternative to reCAPTCHA
GPTBUSTER | reCAPTCHA | |
---|---|---|
Privacy Fully GDPR/HIPAA/CCPA/LGPD/DPDPA/PIPL compliant - No cookies, no tracking, no external servers | | |
Accessibility WCAG/EAA compliant - Works with screen readers and assistive tech | | |
User Experience Frustration-free - No visual puzzles - Self-verifying proof-of-work | | |
Customization Fully adjustable security - Customize widget behavior and appearance | | |
Advanced Security Comprehensive protection - gptBuster for advanced security | | |
Open Source Core Core available as open-source (MIT) - Free to use and modify with optional commercial gptBuster | | |
The open-source widget and integration libraries provide free integration of GPTBUSTER for websites, apps, and services. While the open-source version’s proof-of-work mechanism offers basic protection, gptBuster delivers enhanced security for mission-critical deployments.
Read the Docs
with GPTBUSTER
Sentinel provides a powerful spam protection platform with simple Docker-based deployment. Read the Docs with gptBuster.
Explore our free, open-source CAPTCHA alternative. Learn how to integrate it.
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GPTBUSTER ® is a trademark registered in EU.
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