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Nullgen AI Blocker

Browser extension · Free forever

Stop AI prompts at the keyboard, not after the fact

Most AI controls react to what already happened. The Nullgen AI Blocker extension prevents the prompt from being typed or pasted in the first place, on any website, in Chrome, Edge, Firefox, and Safari.

Your current browser is not supported. Use Chrome, Edge, Firefox, or Safari.

Other browsers

Free forever. No account required. Installs in about a minute.

  • Chrome
  • Edge
  • Firefox
  • Safari
  • Works on any website
  • 100% on-device processing

  • Runs in your browser

    Detection happens locally. Your prompt is never uploaded to us.

  • No account needed

    Install and you are protected. Nothing to configure, nothing to sign up for.

  • Free forever

    Prompt blocking is free, permanently. Pro is optional and adds management and the apps.

What the extension does

One job, done well: text never makes it into an AI prompt box.

  • Blocks prompt input

    Typing and pasting into AI chat inputs is prevented, on any website and in any kind of chat box.

  • Your privacy, protected

    Nothing you type is uploaded or stored. Detection runs entirely in your browser, so your data always stays on your computer.

  • Detection is automatic

    It spots AI chat boxes wherever they appear, including brand-new assistants you have never heard of.

  • One-minute setup

    Install it from your browser’s store and it starts working immediately. No proxy, no certificate, no network changes.

How it works

  1. 01

    Install the extension

    Add it from your browser’s store on any computer you want covered.

  2. 02

    Prompts are recognized

    As pages load, the extension identifies inputs that behave like AI chat prompts.

  3. 03

    Input is blocked

    Text entry into those fields stops working, so nothing can be submitted to the model.

Pick your browser

One install per browser profile. Every listing is the same extension.

Pro

Pro for managed browsers

Everything in the free extension stays free. Pro adds the controls you need when the browser is not your own.

Start a free trial

  • Enroll every browser

    Link browsers to managed users with a 6-digit code, or force-install through Google Workspace, Jamf, Intune, or Group Policy.

  • Pinned so it stays on

    Enforcement keeps the extension installed so it cannot be turned off or uninstalled.

  • Policies per person

    Allow or deny AI on specific websites for the users you choose, synced in real time.

  • Access requests

    Users ask for AI access from the block itself. Approvers approve or deny for a set time.

After installing the extension

Confirm it works

Try an AI chat in a new tab or refresh a page that was already open.

  1. 01

    Open an AI assistant

    ChatGPT, Claude, Gemini, or any other chat — in a new tab, or refresh their page.

  2. 02

    Try typing in the prompt

    Click the prompt and type or paste.

  3. 03

    Block happens immediately

    You’ll see a notice that the prompt is blocked — prompt prevention protection is working.

A few things worth knowing

  • One install per browser profile

    Each browser and profile is separate — install wherever you want protection.

  • New assistants are covered automatically

    You don’t maintain a site list. Detection finds AI prompt boxes as they appear.

  • Prompt text stays on this device

    Detection runs locally. We never read, store, or transmit what someone typed into a prompt.

Protecting more than one device?

Family, Education, and Enterprise plans add enrollment, access requests, policy management, and an admin portal.

Explore plans

Common questions about the extension

  • Is the free version limited or a trial?

    Neither. Prompt blocking is the free product and stays free. Pro adds the admin portal, fleet management, and the mobile and desktop apps on top.

  • Do you see what people type?

    No. Detection runs in the browser and prompt text is not sent to us. The free version has no account, so there is nothing tied to you.

  • Does it only block ChatGPT?

    No. It finds AI prompt boxes on any website, including new assistants, and leaves the rest of the page usable.

  • Which languages are supported?

    Only English websites are supported today. We plan to support other languages in the future.

  • Can it be uninstalled by the person using the device?

    Yes. The browser extension, the mobile app, and the desktop app can all be uninstalled. Nullgen Pro adds enforcement to pin the extension and apps, alongside OS-level family and enterprise controls.

The rest of the suite

Every product links to the same dashboard, so policies and approvals follow the person, not the device.

Try the extension for free

It takes a minute to install with no commitments.

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