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Kestrel review

Free#6 of 25 in Game FPS Counters

A detailed, open-source Windows overlay for frame-time and system telemetry.

7.9/10Editor score
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Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026

Kestrel is a portable Windows desktop overlay for monitoring game frame timing and system performance. It is aimed at Windows enthusiasts who want detailed per-game telemetry without installing a kernel driver. The single executable displays FPS, frame intervals, 1% and 0.1% lows, per-frame GPU time, CPU and GPU utilization, power, temperatures, memory, display data, and battery information. It supports Windows 10 version 1607 or newer on 64-bit systems.

Its open-source, free model keeps access straightforward, while the telemetry depth goes beyond a basic FPS counter. Kestrel can identify whether a run is CPU- or GPU-bound, draw rolling graphs with configurable redraw rates, and monitor battery health, charge, cycle, and wear. Per-game profiles control visible metrics, and CSV recording stores per-frame data alongside run summaries for later analysis. JSON settings export and import help carry configurations between setups.

Setup is lightweight because Kestrel runs without an installer, and optional Windows startup or an elevated scheduled task can automate launching it. Frame-timing metrics require administrator rights, however, and exclusive-fullscreen games cannot receive the overlay because Kestrel does not inject into game processes. Support is community-based. Choose Kestrel if Windows compatibility, granular frame analysis, and exported run data matter most; choose another counter if you need non-Windows support or overlays in exclusive-fullscreen games.

Kestrel pros and cons

  • Where it wins
    • Per-frame timing with 1% and 0.1% lows plus CPU/GPU-bound detection
    • CSV run recording, rolling graphs, profiles, and JSON settings transfer
    • Portable executable monitors GPU, CPU, memory, power, temperatures, and battery
  • Where it doesn't
    • Frame-timing metrics require administrator rights
    • Cannot overlay exclusive-fullscreen games
    • Windows-only desktop app with community support

Kestrel fact sheet, pricing and score →

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