LapTrace

Record a session, understand every lap, then synchronize telemetry with action-camera footage and render a clean overlay—all locally on your iPhone.

Turn your iPhone into a local-first telemetry recorder and video companion for karting, cycling, and outdoor activities.

RECORD THE SESSION • Start a karting, road-cycling, or outdoor session in seconds. • Capture timestamped location and motion telemetry with source and quality information. • Follow recording duration, current speed, quality, and active Apple-device sources with a local Live Activity. • Road cycling includes moving-time auto-pause, with a per-ride option to turn it off; raw telemetry and elapsed time continue. • Open LapTrace on a paired Apple Watch to add a separate Watch location stream to the active iPhone recording. • Keep the original sensor log while LapTrace calculates useful derived values.

UNDERSTAND THE DRIVE • Review your route, speed, distance, and telemetry quality. • Optionally download nearby public kart-track data from OpenStreetMap after a clear permission prompt; normalized track data is cached locally for offline use. • When route evidence is strong, review the matched track layout, edit an unsaved start/finish suggestion, and compare an additional track-constrained route. • Set a non-destructive driving range to exclude setup or shutdown time from kart review and flat exports while preserving the complete raw recording. • When Watch data is available, compare iPhone, Apple Watch, and combined routes, observed rates, distance, gaps, and source timing. • See current, previous, and best lap times. • Compare lap deltas and inspect a speed trace without a wall of engineering data. • Configure a directed start/finish line and reusable track when needed.

SYNC ACTION-CAMERA FOOTAGE • Import video from Photos or Files. • Align footage and telemetry with dependable coarse and fine offset controls. • Set video and telemetry in/out points. • Preview speed and lap values at the selected moment.

CREATE A SHAREABLE VIDEO • Choose from reusable overlay presets. • Adjust overlay position, scale, and opacity. • Render the overlay with AVFoundation, then save or share the finished video.

OWN YOUR DATA • Export CSV, JSON, GPX, FIT, or a documented LapTrace session archive where appropriate. • No account, LapTrace backend, analytics, tracking, or automatic upload. • Telemetry, imported media, projects, and exports remain local to your devices until you explicitly save or share them.

LapTrace clearly labels each session's telemetry source and quality. FIT exports include timestamped position, altitude, speed, distance, lap, session, and activity records.