Turn Your Smartphone into a Surveillance Detector: Fieldwatch for Android

Security creator @CopyRebeldia highlights Fieldwatch, an open-source Android app that passively scans ambient Wi-Fi and BLE signals to identify up to 242 survei

tau · October 3, 2026

#android #security #open-source #privacy #fieldwatch

Turn Your Smartphone into a Surveillance Detector: Fieldwatch for Android

Security and privacy creator @CopyRebeldia highlighted 'Fieldwatch', an open-source Android security tool published on GitHub by developer @OGridPete (OffGridPete). By leveraging the smartphone's built-in wireless receivers, Fieldwatch functions as a practical privacy utility to detect and identify nearby surveillance hardware and ambient radio signals in real time.

Fieldwatch open-source Android counter-surveillance app interface and Wi-Fi BLE device detection screen

Image source: CopyRebeldia (@CopyRebeldia)

Fieldwatch Overview: Off-Grid Receive-Only Signal Observer

Fieldwatch transforms an Android smartphone into a receive-only radio signal observer. Distributed under the MIT license, the application operates passively without requiring specialized external hardware, utilizing the device's native Wi-Fi and Bluetooth Low Energy (BLE) reception chips.

  • MIT Licensed Open-Source: Transparent source code available for independent security verification.
  • Passive / Receive-Only Operation: Does not transmit outbound signals that could reveal the user's location, functioning strictly by capturing ambient broadcasts.
  • Developer Repository: Hosted publicly on GitHub via OffGridPete/Fieldwatch.

Core Capabilities and Identification of Up to 242 Device Types

By comparing detected wireless packets and broadcast identifiers against a database of device signatures, Fieldwatch categorizes up to 242 distinct device types in real time:

  • Smart Glasses and Camera Devices: Identifies wireless broadcast signals emitted by camera-equipped smart glasses, such as Meta Ray-Ban frames.
  • Location Trackers: Discovers hidden Bluetooth tracking beacons in the vicinity.
  • Police Body Cameras and Surveillance Hardware: Recognizes signals from law enforcement body cameras and acoustic gunshot detection microphones.
  • Drones and Controller Identification: Detects active drones along with pilot location telemetry broadcasts.
  • Follower Tracking Alerts: Alerts the user when a detected beacon or device appears to be moving consistently alongside them.

Local-First Privacy Architecture and Platform Limits

Fieldwatch is engineered with a local-first design to eliminate common privacy risks:

  • No Internet Required (Off-Grid): Operates completely offline with no account registration, cloud synchronization, or remote server dependencies.
  • Network Independence: Scans and analyzes ambient signals normally even in environments with zero cellular or network connectivity.
  • Android-Exclusive: Currently available only on Android. Operating system-level restrictions in iOS block low-level raw Wi-Fi and Bluetooth scanning, preventing an iPhone release.

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