Spotter
This set
Rep 1 · clean
Rep 2 · clean
Rep 3 · drifted
Rep 4 · clean
Rep 5 · clean
Live Computer-vision bar tracking

One set.One fix.

Set your phone on a stand and lift. Spotter traces the bar, compares it to the ideal line, and hands you the single thing to change.

How it works
Free, no sign-up. Your video never leaves your phone.
9:41
Back squat · Set 1 of 4
102 kg · 5 reps
Replay · Rep 3
Max drift
6.2 cm
Concentric
0.42 m/s
Hip depth
-4°
R11.1R21.6 R36.2R42.4 R52.0
Spotter diagnosis
Early hip rise on rep 3
Chest tall, drive your upper back into the bar.
30
Frames per second
0.2"
Tracking precision
56
Exercises supported
0
Taps to start
How it works

Everything the bar
tells you.

One camera, one set, and a read on every rep you just did.

Frame in 10 seconds
0
frames per second
0
taps between reps
Live bar path

Every rep drawn against the ideal line, while you lift.

0″
tracking precision
Joint tracking
One fix per set
Chest up, push the floor away.
Drift flagged
6.2cm
On device
56 exercises
SquatBenchDeadliftCurlMachines
Library

Know the line before
you chase it.

56 exercises with the bar path each one should travel, and the two or three ways it usually goes wrong.

2:14
Back squat
Why the bar creeps forward out of the hole, and the cue that pulls it back over midfoot.
Barbell · 3D bar path
2:31
Bench press
The one lift where a curved path is correct. Learn the J-curve and how far is too far.
Barbell · 3D bar path
2:45
Machines & cables
Fixed rails set the path, so Spotter grades tempo, range of motion and stall points instead.
Machine · Tempo & ROM
Privacy

Your footage never
leaves your phone.

Spotter reads the bar on device. Only the path coordinates are sent for analysis, and they are thrown away once you have your fix.

1
Your set is filmed
The video is written to your camera roll and nowhere else.
Stays on device
2
Coordinates are sent
A short list of bar positions. No frames, no faces, no audio.
About 4 KB
3
You get one fix back
The coordinates are discarded as soon as the feedback is written.
Not stored
No account required No data sold No footage shared privacy@spotter.app
Contributions

Built in a weekend.

Spotter was designed and built for the AI Builders Hackathon.

AI Builders Hackathon — Think. Build. Ship.
Computer vision
Bar path traced frame by frame from one phone camera. No markers, no wearables.
AI coaching
Path data is compared against the ideal line, then turned into one plain sentence.
React Native
One build for iOS and Android, with a FastAPI backend doing the heavy analysis.

Your next set can be
your best one.

Prop up your phone, hit record, and find out what one change is worth.

Browse the library
Free to use. No account. Nothing uploaded.