Warning: This app was mostly vibe-coded, but it seems to work.
The speed can drop out, but the app warns if the data is more than 5 seconds old. Location and speed data stays on your device.
If you want, you can install this site to your homescreen:
iOS: Tap Share → 'Add to Home Screen'. Check "Open as Web App" if prompted to avoid the url bar.
Android: Tap Menu → 'Add to Home screen'
The layout is optimized for modern iPhones, but works on most devices.
Please enable location access to continue.