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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
Last edited
September 16, 2026 at 6:58 PM by Venkatraman Chandrasekaran
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