Nullify

Nullify is a free open source Mac and Windows app that detects hidden meeting transcribers on your computer and can scramble audio so AI notes come out unusable.

About Nullify

Nullify is a free desktop app for meeting privacy. It watches the local computer for invisible AI transcription tools and can add an Audio Shield that makes speech-to-text output much less usable. The project is open source under the MIT license. Processing stays on the device. The site says no data is sent to external servers.

The app is aimed at stealth capture, not only visible meeting bots. It looks for process signatures and, for some tools, outbound network traffic. The public detection list includes Granola, Otter.ai / OtterPilot, Fireflies, Read.ai, tl;dv, Fathom, Supernormal, and Tactiq. Coverage is not identical for every tool. Tactiq is listed for network detection. Network detection for Supernormal and Tactiq is still marked as coming soon on the product site.

Audio Shield uses psychoacoustic perturbation. GitHub documents four levels: Stealth, Moderate, Strong, and Maximum. Claimed word error rate gains range from about 15 to 25 percent at Stealth up to full disruption at Maximum. Processing delay is listed as under 50 milliseconds. The shield is meant to keep speech sounding normal to people on the call at lower levels. Strong is described as noticeable noise.

Nullify runs in the system tray or menu bar. It can show a real-time activity log, an audio level meter, auto-start shield on detection, and configurable scan intervals. GitHub is explicit that the app does not kill or block processes. It detects tools and can degrade transcription quality. The Audio Shield feature needs a virtual audio device: BlackHole on macOS or VB-Cable on Windows. Pre-built v0.2.0 downloads on GitHub are macOS disk images for Apple Silicon and Intel. The same release notes say the Windows installer is coming soon.

Key Features

Process detection: Watches local processes for known transcription apps as they start.
Network detection: Flags outbound traffic to known transcription APIs for some tools, including Deepgram and AssemblyAI paths.
Audio Shield: Adds psychoacoustic perturbation so AI transcripts lose accuracy while people can still hear the speaker.
Protection levels: Stealth, Moderate, Strong, and Maximum, with rising disruption and rising audible effect.
Local operation: Runs on the machine, stays in the tray, and does not send conversation data to Nullify servers.
Activity log: Records detection events with a dark UI built for quick checks during a call.

Pricing

Free: $0 The official site and Product Hunt list Nullify as free. No account or subscription is required. Source is available under the MIT license on GitHub.

Use Cases

Detect a stealth transcription app running on your own computer
Add Audio Shield when you think another tool is capturing system or microphone audio
Keep a log of detection events during Zoom, Google Meet, or Microsoft Teams calls
Audit an open source meeting privacy tool before using it on a work laptop
Reduce usable AI transcripts of your outgoing voice without joining a meeting as a bot

Pros & Cons

Pros:

Free and MIT licensed, with public source on GitHub
Combines detection and audio perturbation in one desktop app
Works locally with no Nullify cloud upload of conversations
Names specific tools and detection methods in public docs

Cons:

Does not stop or quit the transcription process itself
Audio Shield needs a third-party virtual audio driver
GitHub v0.2.0 ships macOS builds first; the Windows installer is listed as coming soon
Cannot reliably see a transcriber that exists only on someone else’s computer

Integrations

Zoom, Google Meet, Microsoft Teams, BlackHole, VB-Cable

FAQ

What is Nullify?

Nullify is a free open source desktop app that detects hidden meeting transcription tools on your computer and can apply an Audio Shield that raises errors in AI transcripts.

Is Nullify free?

Yes. The official site lists it as free. No account is required. The GitHub repository uses the MIT license.

Does Nullify quit or block the transcription app?

No. GitHub states that Nullify does not kill or block any process. It detects the tool and can degrade transcription quality with audio perturbation.

Which tools can it detect?

Public docs list Granola, Otter.ai / OtterPilot, Fireflies, Read.ai, tl;dv, Fathom, Supernormal, and Tactiq. Process and network coverage varies by tool.

Will other people hear the Audio Shield?

The product site says the shield is designed not to affect human conversation and to keep your voice sounding normal. GitHub is more graded: Stealth is described as imperceptible, Moderate as a faint hum, and Strong as noticeable noise.

Does it work with Zoom, Google Meet, and Microsoft Teams?

Yes. Nullify is not a meeting-app plugin. It runs on the computer and is documented for use during those calls, including against tools that never appear in the participant list.

What do I need to install?

Download the desktop app. Audio Shield also needs a virtual audio device: BlackHole on macOS or VB-Cable on Windows. GitHub currently publishes macOS .dmg builds for Apple Silicon and Intel.

Is my audio sent to Nullify?

The official site says everything runs on your machine and that no data is sent to external servers.

Can it detect a transcriber on another person’s laptop?

Not as a local process. The Granola guide says Nullify can still protect your outgoing microphone audio with Audio Shield. Direct process detection applies to software running on your machine.

Categories:

Meeting Privacy Software