LibreSpeed browser measurement engine, by Federico Dossena and contributors.
Source: https://github.com/librespeed/speedtest
Pinned upstream revision: aa84692df3f0de19021153ada69572335cff8547
License: GNU LGPLv3, supplied alongside these files.

Unmodified source is retained in this directory. The executable worker at
/speedtest_worker.js was modified on 2026-10-14 to add transfer counters,
per-direction soft byte limits, warm-up/limit flags, HTTP download status
validation, early error handling, and omission of the redundant Content-Encoding
request header for compatibility with globally CORS-enabled providers.
Its complete modified source is served
at that URL. /measurement.mjs manages configuration and worker lifecycle.

Telemetry is disabled. Rates use application bytes (overhead factor 1).
Limits include warm-up and are best effort: browser/network buffers can
transfer additional in-flight data. Upload counters reflect browser progress,
not independently acknowledged receiver bytes.