Backyard Lap Timer
Choose who is driving, which car, and where you are racing.
Drivers
Tap a driver to use them in your next session.
Add driver
Cars
Choose a car or review its setup.
Add car
Tracks
Choose the track for your next session.
Add track
Sharing & access
Invite one of your drivers to a track. Track invitations appear in Community.
Sign in to manage track sharing.
Results
Browse sessions saved on this device or compare cloud track records in Leaderboard.
One best lap per track. Conditions and car describe the winning session. Race totals are grouped only by lap target and require every lap to be valid.
Track records
Cloud records across devices and members of your shared tracks. One best lap per track; best race totals are grouped by lap target. Car and conditions describe the winning result, not separate rankings. Full session details stay on the recording device.
Sign in to view cloud track records.
Race
Open the camera, draw the finish line, and calibrate before starting.
1 Camera & finish line
Camera options & zoom details
Open the camera to see which zoom controls your browser supports.
Draw a line, then calibrate with the track empty.
2 Detection
Open the camera and draw a finish line to begin.
3 Session Setup
Target: 10 laps
Recorded with the session and its record. Conditions and cars do not create separate track lap records.
Choose a track to set the session condition.
Ghost reference
References show best lap and valid laps total. Same track, layout, surface, condition and direction. Invalid laps make a session ineligible as a Ghost reference. Gap and voice update at each completed lap; negative means ahead.
Session: Idle
Live timing
Projection uses completed-lap average after 2 laps, excluding pauses. Ghost gap updates at the line.
Waiting for detection to start.
Lap history
| Lap | Time | Delta to best |
|---|
Session summary
Community
Add drivers, accept track invitations, and compare best times.
Sign in to manage drivers and shared tracks.
Your drivers
Add a driver using their unique Backyard nickname.
Invitations
Driver requests and invitations to race on a shared track.
Settings
Open a group to manage your account or adjust this device.
Account & profile
Sign in or create an account
Keep using the timer without an account. When you sign in, this device’s guest drivers, cars, tracks, and saved sessions are automatically merged into your account. Your original guest copy stays on this device.
Checking sign-in availability…
Profile photo
Uses your account photo, including the Google photo when provided. Upload a personal photo to replace it. Your photo is visible on drivers linked to your account.
Your nickname is a unique @name other drivers use to find you (3–24 letters, numbers, underscores or hyphens). Your public name is shown on leaderboards.
The app automatically backs up driver, car and track profiles, car setup notes, and best-result summaries. It never uploads individual laps, complete session files, camera settings, or video. First sign-in automatically merges this device’s guest history into its account copy.
Import a backup file
Use this only to bring in an exported JSON backup from another browser or device. Guest data on this device is merged automatically at sign-in.
No backup selected.
Delete cloud data
This removes your cloud profile and shared records. Your local copy remains on this device.
Two-device setup (optional)
This device only is the default. For remote operation, open this app on two devices connected to the same Wi-Fi. For account pairing, sign in to the same account and enable visibility on both devices. Cloudflare only introduces the devices; camera video, controls and timing then use the local connection. Devices must be able to reach each other on the same Wi-Fi. Offline QR pairing remains available without an account or internet. Timing and saved results stay on the Sensor. Pair before mounting the Sensor phone.
Pair devices from your account
Visibility is off by default. Both devices must opt in. The Sensor approves each connection. No network scan is performed; the list shows devices available through your account, and local connectivity is checked when pairing.
Sign in to the same account on both devices, then enable visibility.
After connection, visibility stops and the Cloudflare pairing connection closes. If your Wi-Fi blocks communication between devices, pairing will fail; video will never be relayed through Cloudflare.
Offline QR alternative
1. Create an offer and have the Viewer scan it.
2. Scan the answer displayed on the Viewer.
1. Scan the Sensor offer QR, then show the answer QR to the Sensor.
2. Keep this answer QR visible until the Sensor scans it.
Single-device mode.
Finish line settings
Zone size controls the area watched around the line. Direction refers to movement in the camera image, regardless of how the line was drawn.
Detection sensitivity
Calibration sets the threshold for the current lighting. Change this manually only if detection needs tuning.
Phone & detection test
Open the camera, draw the finish line, and start detection on Race. Return here while detection is running, then make a pass across the line. This panel records the analyzer frame at the center-line timestamp used for timing and reports this phone’s observed processing rate.
Precision estimate is one analysis-frame interval at the measured FPS. Camera exposure, motion blur, lighting, and thresholding can add error; this is not a laboratory accuracy measurement.
Zone motion: A — · center — · B —
Camera setting: — FPS · requested: 60 FPS
Screen Wake Lock is inactive.
Frame used to mark the passage time
No passage captured yet. Start detection and make a car pass the finish line.
Last candidate: —
This experimental detector estimates a crossing from motion through zones A, center and B. It does not identify a specific car; people, shadows, camera shake and other movement may trigger it. Processing and captured frames stay on this device.
Lap timing
Crossings sooner than the minimum lap time are detected but ignored by the lap timer. This protects against duplicate triggers.
Sound alerts
Install the app
Add Backyard Lap Timer to your home screen for quick access. Open this page in the browser listed below first.
iPhone / iPad · Safari
- Open this page in Safari.
- Tap Share (the square with an up arrow).
- Tap Add to Home Screen (you may need to scroll).
- Tap Add to confirm.
Android · Chrome
- Open this page in Chrome.
- Tap the three-dot menu ⋮.
- Tap Install app or Add to Home screen.
- Confirm Install or Add.
Computer · Chrome / Edge
- Click the install icon in the address bar, if shown.
- Choose Install.
- Alternatively, open the browser menu and select Install Backyard Lap Timer.
If an install option does not appear, use the latest version of a supported browser and check its menu. Installing adds an app shortcut; your sessions remain stored on this device.
Camera choice, zoom, zone size, direction, sensitivity, minimum lap, alerts, and session length are remembered here. A different phone keeps its own settings. Clearing browser site data removes them.
Viewer / Controller
Waiting for Sensor…
Drag on the camera preview to set the finish line. The Sensor applies the line and all controls.
Save this session?
Only saved sessions count toward records. Discarding will not update history or cloud records.
Consistency: —