STAmaster
Train smarter, hold longer. Your personal Static Apnea coach — now with live SpO2.
Train smarter, hold longer. Your personal Static Apnea coach — now with live SpO2.
Built for freedivers at every level. All features are completely free.
Millisecond-accurate timing with real-time contraction marking, voice coaching cues, and background mode so your screen can stay off.
Full library of training tables for CO2 tolerance and O2 extension. Create custom tables or pick from a curated library by level.
Unlimited session history, heart rate charts, and performance trends. See your improvement over weeks and months.
Personalized training plans that adapt to your level. Post-session analysis with actionable tips and plateau detection.
Real-time heart rate via Bluetooth HR monitors (Polar, Garmin, Wahoo), Apple Watch, or pulse oximeter. Pick your preferred source for any session. Morning HRV and resting heart rate from Apple Health for readiness.
Connect a Lepu PC-60FW pulse oximeter for real-time oxygen saturation, perfusion index, and a customisable hypoxia alert. Every hold gets its own SpO2 trajectory in the summary.
Mandatory buddy check for wet static training. Because the #1 rule in freediving is: never train alone in water.
Stream your Amazfit heart rate into STAmaster during training, via Apple Health.
Stream SpO2, heart rate, and perfusion index directly from your fingertip.
Every feature. No paywalls. No subscriptions. No catch.
Last updated: 16 May 2026
STAmaster is a freediving Static Apnea training app for iOS. This policy explains what data the app collects, how it is used, and your rights.
Breath-hold durations, personal bests, contraction onset times, session notes, training table configurations, and onboarding preferences are all stored locally on your device using SwiftData.
Your data stays on your device. If you back up your iPhone, your STAmaster data is included in the backup.
With your explicit permission, STAmaster reads the following from Apple Health for training readiness:
Real-time heart rate during training sessions is provided by Bluetooth HR monitors, Apple Watch, or a connected pulse oximeter — not from HealthKit. Health data is never uploaded, transmitted to any server, or shared with any third party.
When you pair a Lepu PC-60FW (or compatible) pulse oximeter, STAmaster reads SpO2, pulse rate, and perfusion index directly over Bluetooth Low Energy. Samples are stored locally with the rest of your training data and are never written back to Apple Health (sensor lag would pollute Health app data) and never uploaded anywhere.
STAmaster requests Bluetooth permission only to connect to heart rate monitors and pulse oximeters that you explicitly pair. The app does not scan for or track unrelated Bluetooth devices.
STAmaster is currently completely free with no in-app purchases. All features are available to every user at no cost.
STAmaster contains no third-party SDKs, analytics services, or advertising networks. There is no external communication with any server.
STAmaster requests permission to read:
These are used solely for the training readiness score. Real-time heart rate during sessions comes from Bluetooth HR monitors or Apple Watch, not HealthKit.
You can revoke these permissions at any time in Settings > Privacy & Security > Health > STAmaster.
The app uses background audio mode to keep the timer running when your screen locks. It only plays coaching cues and does not record audio.
All data is stored exclusively on your device. To delete all STAmaster data:
STAmaster is rated 4+ and does not knowingly collect data from children under 13. Breath-hold training is a physical activity; all users should seek medical advice before training.
Freediving and breath-hold training carries inherent risks. STAmaster enforces a mandatory buddy-check before any wet static (in-water) training session. Never train breath-holding alone in water. This app is a training aid, not a safety device.
We may update this policy from time to time. The "Last updated" date at the top will reflect any changes. Continued use of the app after changes constitutes acceptance of the updated policy.
Last updated: 19 March 2026
By downloading or using STAmaster, you agree to these Terms of Service. If you do not agree, do not use the app.
STAmaster is a training tool for Static Apnea (breath-hold) practice. It provides timers, training tables, progress tracking, and coaching guidance to support your freediving training.
STAmaster is a training aid, not a medical device. The app does not diagnose, treat, cure, or prevent any medical condition. Heart rate, HRV, and SpO2 data displayed in the app are for informational training purposes only. Always consult a qualified medical professional before beginning any breath-hold training programme.
Never practise breath-holding alone in water. Breath-hold training carries inherent risks, including shallow water blackout, which can result in drowning. STAmaster enforces a buddy-check before wet static sessions, but the app cannot guarantee your safety. You are solely responsible for training in a safe environment with a qualified safety buddy present.
You acknowledge that breath-hold training is an inherently risky physical activity. By using STAmaster, you voluntarily assume all risks associated with this activity. Code3 is not liable for any injury, loss, or damage arising from your use of the app.
You agree to use STAmaster only for its intended purpose of personal breath-hold training. You will not reverse-engineer, decompile, or attempt to extract the source code of the app.
STAmaster and all associated content, design, and branding are the property of Code3. You may not reproduce, distribute, or create derivative works from any part of the app without written permission.
We strive to keep STAmaster available and functional, but we do not guarantee uninterrupted access. We may update, modify, or discontinue features at any time.
To the maximum extent permitted by law, Code3 shall not be liable for any indirect, incidental, special, consequential, or punitive damages arising from your use of STAmaster.
We may update these terms from time to time. The "Last updated" date at the top will reflect any changes. Continued use of the app after changes constitutes acceptance of the updated terms.
Questions about these terms? Email support@code3.io
Having trouble or have a question? We're here to help.
Email us at support@code3.io
Yes, STAmaster is completely free. Every feature is included — no paywalls, no subscriptions, no hidden costs. Just download and start training.
Absolutely. Apple Watch and Bluetooth HR monitors are optional. The core timer, tables, and coaching features work on iPhone alone.
Your training data is stored locally on your device. If you back up your iPhone via iCloud or Finder, your STAmaster data is included in the backup.
Yes. Dry static (on land) does not require a buddy check. The buddy-check safety prompt only appears for wet static sessions.
The Lepu PC-60FW is fully verified end-to-end. Other Lepu models that speak the same protocol (PC-66B, Oxysmart, Wear O2) may work but are not guaranteed. If you have one of these, try pairing it via Profile › Pulse Oximeter and email us if it doesn't connect.
Open any STA Free Hold or Table setup screen and tap the heart rate row. A picker appears with Auto, Pulse Oximeter, BLE Strap, and Apple Watch. Auto prefers the oximeter when connected, then a strap, then your watch. Your choice persists across sessions.
Fingertip pulse oximeters typically read about 10 seconds behind your true arterial saturation, and the lag gets longer during a breath-hold — the dive response shunts blood away from your fingers to protect your core. This is physics, not a bug. STAmaster captures samples for 30 seconds after the hold ends so the real oxygen nadir gets recorded properly.
After you've completed 10 distinct training sessions where you marked at least one contraction. The card combines your best CO2 tolerance (latest first-contraction time) with your best struggle endurance (longest time after first contraction) to project a realistic ceiling.
STAmaster requires iOS 17 or later.
Yes! STAmaster is now available on Android. Get it on Google Play — a native build with full feature parity.