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Nullgen AI Blocker

Free browser extension

Stop AI prompts at the keyboard, not after the fact

Most AI controls react to what already happened. Nullgen AI Blocker prevents those AI prompts from happening in the first place. You get immediate prevention, not damage control afterward.

Download Free ExtensionSee who it’s for

Works in Chrome, Edge, Firefox, and Safari. No account, no sign-up, no cost.

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

  • Runs on device

    Detection happens locally in the browser. 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 extra control and features.

The gap

Blocking the whole site does not work anymore

Domain blocklists break the moment a new assistant launches, and monitoring tools only tell you about the essay, the leaked snippet, or the pasted customer list after it is gone. Blocking at the prompt keeps the useful web intact while the one risky action — typing into an AI prompt — stops working.

Domain blocking

Blocks entire websites. Breaks useful tools and lags behind new assistants.

  • Breaks helpful sites the moment they add AI
  • Needs a constantly updated blocklist

Prompt blocking

Keeps the site usable. Stops the one risky action: typing into an AI prompt.

  • Works on new assistants automatically
  • Leaves the rest of the web intact

What the free version does today

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 in your computer.

  • Detection is completely automatic

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

  • One-minute setup

    Install the extension 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 machine 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.

Who it’s for

One extension, three very different reasons to use it

Prompt blocking is completely free. The Pro plans add features and admin controls for parents, teachers, and organizations.

Pro

Centralized management

Everything in the free version stays free. Pro is for people who need to manage more than their own browser.

Start a free trial

  • Users and devices

    Add the users you manage, choose their approvers, and enroll their devices.

  • Access requests

    Users can ask for AI access. Approvers can approve or deny requests.

  • Real-time policy sync

    Policy changes reach enrolled browsers as they are saved, without waiting for a restart.

  • Deploy and pin

    Force-install on managed browsers and pin it so it cannot be turned off or uninstalled.

Common questions

  • Is the free version limited or a trial?

    Neither. Prompt blocking is the free product and stays free. Pro adds the admin portal and fleet management 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?

    In the free version, yes: whoever controls the browser profile can remove any extension. However, with the Pro plan you can enforce installation that cannot be tampered with by the end user.

Try the extension for free

Extension takes a minute to install with no commitments.

Download Free Extension