1. Professional map data, not guesswork

Apple Maps shows a speed limit while navigating, but Apple exposes no API for other apps to read it. So SpeedGuardian Pro licenses the same class of data your car's built-in navigation uses: HERE Technologies road-graph data, with OpenStreetMap as a fallback for rural roads where commercial coverage thins out. Every road segment carries its posted limit.

2. Knowing which road you're actually on

GPS puts you within a few meters — but a frontage road runs parallel to the interstate with a 50 mph difference. The app snaps your position to the road graph using your heading and speed, caches the segments around you, and re-checks as you move. That snap is the difference between a useful alert and a false alarm.

3. Looking ahead so you hear it early

This is the flagship. SpeedGuardian Pro projects your path forward along your heading — a ray-cast down the road you're driving — and queries the limits you haven't reached yet. When the zone ahead is lower, you hear “New limit ahead” while the sign is still half a mile away, with the distance counting down live. It refreshes every 100 meters of travel or whenever you turn more than 15 degrees.

4. What happens when data is missing

Honesty over guessing: when the database has no limit for a road, the app shows “--” and stays quiet. It never invents a number. Rural coverage has real gaps, construction zones change faster than any database, and school-zone hours are inconsistent. When the app and a posted sign disagree, the sign is always right — that rule is printed inside the app, in our terms, and here.

5. Privacy is an architecture, not a promise

Limit lookups send coordinates to the map provider and nothing else — no identity, no history, no account. Your driving events for the weekly report are computed and stored on the phone. Delete the app and they're gone. We couldn't sell your driving data if we wanted to; we never receive it.