Hi Product Hunt, I'm a solo developer from Japan. I built SpeedShot because of a question that comes up on every walk near a busy road: that car just blew past — how fast was it, really? There was never a quick way to answer that without a radar gun. So I built one out of a phone camera. Point it at traffic, or drop in a clip you already shot, and on-device AI detects every vehicle, tracks it frame by frame, and works out its real-world speed from the geometry of the road itself — no GPS, no radar, no manual setup. A few things I put real work into: - Automatic road calibration. The app finds the vanishing point and lane-marking spacing in the clip and builds a scale model of the scene before it ever shows a number. - Real object detection, not a filter. An on-device CoreML YOLOX model finds cars, motorcycles, buses and trucks; a Kalman-filtered tracker follows each one. - Fully offline. No account, no network calls, no analytics — nothing ever leaves the phone. - One optional one-time purchase after 2 free analyses. No subscription. I built it in a few weeks. The hard part wasn't the object detection — it was making the speed math trustworthy without ever touching GPS or a second reference camera. One honest caveat up front: the speed shown is an AI estimate for reference and fun, not a certified measurement — it's not meant for enforcement or as evidence. I'd love to hear what you think: would you use this to settle an argument about how fast something was going, or is a phone camera never going to feel trustworthy enough for that?

SpeedShot

An iPhone camera that turns into an AI speed gun

An iPhone camera that turns into an AI speed gun