FROST Local OPFS timing

Browser SSD timing

FROST Demonstration

This page runs a local, self-contained demonstration of storage-access timing behavior in the browser. It prepares an OPFS file on this device, samples randomized reads, and visualizes the resulting trace.

Disclosure

This is a responsible security research demo. No third-party websites are opened, no measurement data is uploaded, and the benchmark stays inside this browser's local Origin Private File System. After testing the OPFS file can be deleted using the "Delete OPFS files" button in the demo panel below.

Run local demo

Start guide

Before you run the trace

The demo creates a local OPFS file in this browser, reads random chunks from it, and plots how long those reads take. Nothing is uploaded and no other websites are opened by the demo.

Quick start

  1. Choose an OPFS file size larger than your available RAM.
  2. Choose a finite duration, or Infinite for a rolling trace.
  3. Start the measurement.
  4. Open websites or desktop apps in parallel.
  5. Watch how the trace changes while reads are running.

Checklist

  • Use a desktop Chromium-based browser for the most consistent OPFS behavior.
  • Pick an OPFS file size. The file should be larger than available RAM; otherwise reads may be served from cache.
  • Keep the default 4 KB read chunk first, then experiment with other sizes.
  • Use the Y axis slider if spikes are clipped or too small to inspect.

What you are seeing

  • Trace: local read timings over time. Spikes mean individual reads took longer.
  • Median: the typical read time during the run.
  • 95th percentile: the slower tail of reads, useful for spotting variance.
  • CSV export: the raw local timing samples for your own inspection.

Interactive measurement

Local OPFS timing trace

Ready

Samples

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Median

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95th percentile

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Max

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Read time share

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