Nullgen AI Blocker

Nullgen AI Blocker is a free browser extension that stops AI prompts from being typed or pasted into any website's chat input. Unlike monitoring tools that merely report what happened, this extension blocks the action at the keyboard, so nothing reaches the AI model. It works on Chrome, Edge, Firefox, and Safari, requires no account or sign-up, and processes everything locally in your browser. That means your keystrokes never leave your device. The extension automatically detects AI prompt boxes on any page, including brand-new assistants you haven't heard of, and leaves the rest of the site fully functional. Setup takes about a minute: install it from the browser store and it starts working immediately. For organizations that need more control, Nullgen offers a Pro plan with a dashboard for managing users, devices, and policies, including force-install and pinning so the extension can't be removed. But the core prompt-blocking feature stays free forever. The tool is designed for three main groups. Parents can install it on family computers to keep homework in their child's own words without constant supervision. Educators can enforce academic integrity on school-managed devices with zero-touch provisioning. IT and security teams can prevent employees from leaking proprietary data to public LLMs and shut down shadow AI usage. Because the extension works on any website, it covers ChatGPT, Gemini, Claude, and any future AI assistant without needing an updated blocklist. The privacy angle is genuine: detection runs locally, and no text is uploaded or stored. For a tool that does one thing clearly, Nullgen AI Blocker is refreshingly simple.