FormFix vs 3DSeg/JointAngles
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
FormFix
This AI-powered app analyzes your lifting form in real-time, offering instant feedback and corrections for exercises like squats. Record and review your lifts in slow motion to refine technique and achieve your fitness goals.
- Real-time AI form tracking
- Instant feedback on technique
- Detailed analysis for squats
- Slow-motion lift review
- Technique refinement
- Performance enhancement
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Introducing our AI-powered lifting app that tracks your body mechanics in real time, providing instant feedback on your form. With detailed analysis and corrections for squats, you'll learn exactly where improvements are needed. Plus, record your lifts to review your angles in slow motion, allowing you to refine your technique and enhance your performance. Perfect your lifts and reach your fitness goals with our innovative tool. In the world of strength training, proper technique is paramount. Whether you’re a beginner or a seasoned lifter, mastering your lifts Terms of Use: https://app.formfix.com.co/terms-of-service Privacy Policy: https://app.formfix.com.co/privacy-policy
3DSeg/JointAngles
This app measures three-dimensional angles of body segments and joints in real-time using your iPhone's motion sensors. It is designed for researchers, clinicians, and trainers to analyze movement without external hardware. Data can be exported for further analysis.
- Real-time 3D angle display at 60 Hz
- Six selectable Cardan/Euler rotation sequences
- Calibrate to any starting position
- Built-in angle time-series plot
- CSV export via iOS Share Sheet
- Works completely offline
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3D Seg/Joint Angles measures three-dimensional Cardan/Euler angles of body segments and joints using your iPhone's built-in motion sensors — no external hardware required. Designed for biomechanics researchers, clinicians, physiotherapists, athletic trainers, and students, the app uses your iPhone's accelerometer, gyroscope, and magnetometer to compute the three rotational angles (about the X, Y, and Z axes) that describe how a body segment or joint has moved from a defined starting position. HOW IT WORKS Place the iPhone on a body segment (e.g., thigh, shank, forearm). Press "Set Initial Position" to define the reference frame. The app then continuously reports the three angles — in degrees — that describe the 3D rotation from that starting position to the current position, in real time at 60 Hz. ROTATION SEQUENCES Six standard Cardan/Euler rotation sequences are supported: • X-Z-Y (default, recommended for most lower-limb joints) • X-Y-Z • Y-X-Z • Y-Z-X • Z-X-Y • Z-Y-X Select the sequence that matches your anatomical convention. Angles are always displayed in X, Y, Z order regardless of the sequence chosen. PHONE AXES • X axis — points to the right side of the phone (medial-lateral; flexion/extension) • Y axis — points toward the top of the phone (longitudinal; internal/external rotation) • Z axis — points out of the screen (anterior-posterior; abduction/adduction) Positive and negative angle signs follow the right-hand rule applied to each physical axis of the phone. RECORDING AND EXPORT Start and stop recording with a single tap. After recording, the three angles are plotted over time directly in the app. Export the data as a CSV file via email, AirDrop, or any share destination for further analysis in Excel, MATLAB, or R. KEY FEATURES • Real-time 3D angle display at 60 Hz • Six selectable Cardan/Euler rotation sequences • Calibrate to any starting position • Built-in angle time-series plot • CSV export via iOS Share Sheet • Works completely offline — no internet required • No account or login needed • All data stays on your device IMPORTANT NOTES • For accurate results, hold the phone still during calibration • The Z axis requires the magnetometer to be valid — keep the phone away from strong magnetic fields • This app is intended for research, education, and rehabilitation purposes. It is not a certified medical device.
Screenshots
Verdict
The clearest difference is in-app purchases: 3DSeg/JointAngles at none against FormFix's 2. FormFix's advantage is iOS requirement (15.6 vs 26.2). On price, rating, ratings volume and ads there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
Both are free to download. FormFix sells 2 in-app purchases, starting at $8.99 per month. 3DSeg/JointAngles asks for nothing beyond the download.
On the App Store both sit at effectively the same score — 5.0 for FormFix against 5.0 for 3DSeg/JointAngles. Both are backed by a comparable volume of ratings — 1 and 1 respectively.
| Parameter | FormFix | 3DSeg/JointAngles |
|---|---|---|
| Price | Free | Free |
| Rating | 5.0 (1 ratings) | 5.0 (1 ratings) |
| Positive reviews | 100.0% of reviews | — |
| Number of ratings | 1 | 1 |
| Update frequency | Every 3 weeks | — |
| Ads | No | No |
| In-app purchases | Yes | No — better |
| Monetization | Freemium | Free — better |
| Devices | iPhone, iPod | iPhone, iPad |
| Requires iOS | 15.6 — better | 26.2 |
| Further details — not scored | ||
| Size | 67 MB | 5 MB |
| Age rating | 4+ | 4+ |
| Developer | Solomon Haberkost | Boyi Dai |
Customer experience
FormFix
3DSeg/JointAngles
In-app purchases
FormFix
- 1 Month Premium7 Days trial$8.991 Month
- 1 Year Premium7 Days trial$99.991 Year
3DSeg/JointAngles
No in-app purchases









