Speed Test Pro by Libor Benes (Dr. B)

Speed Test Pro is a lightweight, privacy-first Firefox extension that measures your real Internet connection speed (ping, download, and upload) entirely client-side using pure JavaScript — no external speed-test APIs or third-party services are needed.

Modern browsers can measure speed directly, and Speed Test Pro leverages exactly this capability to exactly measure Internet speed with a professional-grade multi-stream approach:
• Ping/Latency: Lightweight HEAD requests with automatic fallback.
• Download: Progressively larger dummy files (100 KB → 500 KB → 1 MB).
• Upload: Random binary data blobs POSTed in multiple sizes (50 KB → 100 KB → 200 KB).

Results appear instantly in a clean popup with a live progress bar. Every test is automatically saved to persistent local history (IndexedDB) and can be exported as a perfectly formatted JSON file with timestamps.

Features:
• One-click full speed test (ping + download + upload).
• Real-time progress bar with clear status messages.
• Beautiful, modern popup UI with large readable metrics.
• Persistent local history (survives browser restarts).
• Export entire history as speedtest_export_YYYY-MM-DDTHH-MM-SS.json
• Scrollable history modal + one-click Clear All.
• Automatic last-result display when you open the popup.
• 100% client-side — nothing leaves your browser.

Ideal For:
• Remote workers, gamers, and streamers checking connection quality.
• Troubleshooting slow internet or high latency.
• Monitoring ISP performance over time.
• Keeping a personal archive of speed tests for parsing and analysis.
• Anyone who wants accurate results without ads or heavy apps.

Security-First Architecture:
• Completely client-side — no external APIs or services beyond the minimal public Cloudflare endpoints needed for measurement.
• No data collection, no telemetry, no tracking.
• Explicitly declared “no data collection” in the manifest.
• All tests and history stay on your machine.

Technical Details:
• Works on Firefox 140.0+ (64-bit desktop).
• Pure JavaScript implementation (no external libraries).
• Multi-stream testing for better real-world accuracy.
• Lightweight and fast (~2 seconds per test).
• Runtime Execution RAM Footprint: ~33 KB (manifest.json + popup.html + popup.css + settings.js + background.js).
• Total Extension Download/Install Size: ~73 KB (including README.md).

Note on Accuracy:
Browser-based tests provide excellent real-world estimates, but results can be affected by network conditions, background processes, and browser throttling. They are not laboratory-grade measurements.

Test Speed Test Pro on any connection — the results are accurate, the export is clean, and your data never leaves your machine.