FT8/FT4 Browser Decoder

Tracking since Apr 1, 2026.

Changelog

• May 9, 2026
  description

  FT8/FT4 Browser Decoder decodes FT8 and FT4 directly from browser tab audio.
  
  FEATURES:
  • Real-time FT8 and FT4 decoding using WebAssembly
  • Waterfall spectrum display (200-3000 Hz)
  • Automatic time synchronization
  • CSV export of decoded messages
  • CQ message filter
  
  USAGE:
  1. Open a WebSDR (websdr.org, kiwisdr.com, etc.)
  2. Tune to an FT8/FT4 frequency:
     - FT8: 7.074, 10.136, 14.074 MHz USB
     - FT4: 7.0475, 10.140, 14.080 MHz USB
  3. Click the extension icon
  4. Click Start
  
  DETAILS:
  • Sample rate: 12000 Hz
  • Slot time: 15s (FT8) / 7s (FT4)
  • Decoder: ft8js WASM library
  
  PRIVACY:
  • No data collection
  • No external servers
  • No tracking or analytics
  • All processing happens locally in your browser
  
  OPEN SOURCE:
  MIT License - Contributions welcome
  https://github.com/Transwarp8/ChromeFT8

  FT8/FT4 Browser Decoder decodes amateur radio FT8 and FT4 signals directly from browser tab audio. Works great with WebSDR and KiwiSDR sites, with no external radio software or virtual audio cable required.
  
  FEATURES:
  • Real-time FT8 and FT4 decoding using WebAssembly
  • Optional persistent Chrome side panel for longer monitoring sessions
  • Waterfall spectrum display for the 200-3000 Hz audio passband
  • Automatic time synchronization for FT8/FT4 slot timing
  • CSV export of decoded messages
  • CQ-only message filter
  • Local browser-based processing
  
  USAGE:
  1. Open a regular WebSDR/KiwiSDR/audio tab. Chrome internal pages such as chrome:// pages cannot be captured.
  2. Tune to an FT8/FT4 frequency:
     - FT8: 7.074, 10.136, 14.074 MHz USB
     - FT4: 7.0475, 10.140, 14.080 MHz USB
  3. Make the WebSDR/audio tab active.
  4. Click the extension icon.
  5. Click Start to decode the active tab audio.
  6. Optional: click Panel to open the longer-running side panel UI.
  
  DETAILS:
  • Target decode sample rate: 12000 Hz
  • Slot time: 15s (FT8) / 7.5s (FT4)
  • Decoder: WebAssembly FT8/FT4 decoder
  • Supported UI: popup plus optional Chrome side panel
  
  PRIVACY:
  • No data collection
  • No tracking or analytics
  • No account required
  • Audio is processed locally in your browser
  • Time synchronization uses a public UTC time endpoint only for clock offset estimation
  
  OPEN SOURCE:
  MIT License - Contributions welcome
  https://github.com/Transwarp8/ChromeFT8

• May 9, 2026
  permissions

  tabCapture, activeTab

  tabCapture, activeTab, sidePanel

Permissions & access

Permissions

tabCaptureactiveTabsidePanel

Host access

None declared

Screenshots

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