Comparison

Frontier X vs Protocol

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

Frontier X

Track your heart health and exercise performance with a smart chest strap monitor. Gain detailed insights into heart rate, rhythms, and training load. Receive personalized feedback and alerts to optimize your workouts and understand your body better.

Highlights
  • Heart Health Monitoring
  • Real-time Heart Rate & HRV
  • Breathing Rate & Strain Tracking
  • Activity Recording (24hrs)
  • Personalized Vibration Alerts
  • AI-enabled Training Insights
  • Metabolic Profile Analytics (Premium)
Features
Read full description

With your Frontier X/X2/X3, track your activity including exercise, rest or sleep to get detailed insights on heart health and exercise performance. This companion app allows you to connect with Frontier X2/X3 - a revolutionary chest strap wearable smart heart monitor and view your recorded data. Trusted by world-class athletes across the globe, the Frontier X2/X3 is a chest-worn Smart Heart Monitor that provides in-depth real-time feedback on your heart health. It can monitor your: - Heart Health - Heart Rate - Heart Rate Variability (HRV) - Breathing Rate - Strain - Rhythms - Training Load - Calories - Stress, and a lot more. • Accurately record your activity like exercise, running, cycling, resting, sleeping, meditation, etc for up to 24hrs with comprehensive heart health insights. • Spot changes in your heart health with Rhythm and Strain. • Train in the right zone without distractions with real-time, personalized, and discreet vibration alerts. • Add health event tags to help you understand how lifestyle choices and behavior affect your health. • Seamlessly integrate with Bluetooth-enabled wearables and third-party devices such as GPS sports watches, bike computers, and more. • AI-enabled algorithms - Receive post-activity training insights, recommendations, and weekly goals. • Frontier X integrates with HealthKit to export your Frontier X activities into the Health app and to read heart rate and biometric data. • IP67 Waterproof up to 1.5 M • Battery: 14+ days of typical use Now get deeper insights and data with Frontier Premium Subscription*: Metabolic Profile Analytics: Track training intensity and the impact of lifestyle changes on metabolic health with key metrics like VO₂ Max, VO₂ Zones, Oxygen Uptake, and Ventilatory Thresholds (VTs). VO₂ Max: Get the most accurate real-time VO₂ Max data. While other wearables estimate using motion and heart rate, our advanced algorithms provides precise VO₂ Max readings outside of a lab, tracking cardiovascular efficiency and endurance potential. Readiness Score: Determine if your body is ready for peak performance or needs recovery. Advanced algorithms use heart rate, heart rate variability (HRV) to guide your daily activities and training. Sleep Stage Analysis: Get a comprehensive understanding of your sleep quality (Webapp). With Frontier's Premium subscription and Metabolic Profile Analysis, tracking your VO₂ max becomes simpler and more precise. *A Paid Frontier Premium subscription is required to access the full feature set . The Premium feature subscription comes with a complimentary 7 days free trial, and continue at a minimal monthly cost starting from USD 14.99, or opt for an annual plan for substantial savings. Please note that prices may fluctuate based on your geographical location, currency, and current exchange rates The Terms of use are available in the app and our website: https://in.fourthfrontier.com/pages/terms-of-use About Fourth Frontier Fourth Frontier is an innovative health-tech company focused on revolutionizing heart health monitoring with its cutting-edge wearable technology. We are the World’s First Smart Heart Monitor. With over 5 billion heartbeats recorded from 120,000+ users across 50+ countries, we are empowering users to understand and manage their heart health in real-time. These features make the Frontier App a comprehensive tool for heart health management and fitness improvement. Download the app today and access the most accurate heart health data available. Apps available for iPhone and Apple Watch.

About

Protocol

Features
Read full description

Protocol is a private logbook for anyone running a hormone, peptide or supplement protocol. It holds what you take, tells you when to take it, does the syringe maths, and shows you what your bloodwork is doing about it. Everything stays on your device. No account. No sign-up. No servers. Nothing to leak. SCHEDULES THAT ACTUALLY FIT Most trackers handle "daily" and give up. Protocol handles every-other-day, every third day, specific weekdays, several doses a day, on/off cycles like 5-on/2-off or 8-weeks-on/4-off, titration ramps that step your dose at set intervals, and fixed start and end dates. Before you save anything, it shows you the next five doses so you can see the schedule is right. REMINDERS THAT HOLD UP Notifications carry Taken and Snooze buttons you can hit from the lock screen. iOS caps every app at 64 pending notifications, so Protocol rebuilds its queue each time you open it and tells you exactly how far ahead you're covered — instead of quietly dropping the ones that don't fit. RECONSTITUTION, DRAWN TO SCALE Enter what's in the vial and how much water you added. Protocol converts each dose to units and draws the fill line on a to-scale U-100 syringe. It handles mg and mcg, tells you how many doses the vial holds, and warns you when a dose won't fit the barrel. SITE ROTATION A body map that colours every injection site by how recently you used it and suggests the one you've left alone longest. Subcutaneous and intramuscular sites, tracked across every compound. BLOODWORK THAT MEANS SOMETHING Log a panel by hand, or copy the text off your results and paste it — Protocol reads it and shows you every value it found for you to confirm before anything is saved. Around 30 markers: total and free testosterone, sensitive estradiol, SHBG, LH, FSH, hematocrit, IGF-1, lipids, liver, PSA and more, each with its own trend line. Two things make the trends readable. Every dose change you make is marked on the chart, so you can see what moved and when. And each panel is tagged trough, mid-cycle or near-peak based on when you drew it relative to your last injection — because a trough reading and a peak reading are not the same measurement. Protocol will also tell you when your next trough window falls. INVENTORY Counts down as you log doses, warns you before you run out, projects the date you'll run dry, and tracks the discard date on a reconstituted vial. STACKS Save an entire protocol as one thing — every compound, dose and schedule — and apply it, edit it, or hand it to someone as a share code. Import theirs the same way. Bring across their structure and set your own doses, or take it as-is. Tag stacks so they stay findable. FOR YOUR CLINICIAN Generate a single PDF: current protocol, adherence, every lab panel with draw timing, and your full dose-change history. Something to hand over instead of describing from memory. ALSO Travel mode shifts every dose time at once. Full light and dark. Haptics. JSON export. WHAT PROTOCOL IS NOT It does not recommend compounds, doses or protocols, and it ships none of its own. It records what you enter and does the arithmetic you ask for. It is not a substitute for a clinician — particularly for anything involving hormones or prescription medication. Reference ranges shown on lab charts are commonly cited adult intervals that vary by laboratory and assay; they are context for your own reading, not targets. PRICING A 7-day free trial, then $39.99 a year. Or pay $99.99 once and own it permanently. No free tier, no ads, no data collection, no upsells. Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/ Privacy Policy: https://wisejester-sudo.github.io/protocol/privacy.html

Screenshots

Frontier X4 screens
Protocol4 screens

Verdict

The call

Frontier X and Protocol are too close to call on the numbers: across 5 compared parameters — price, ads, in-app purchases and device support among them — neither pulls far enough ahead to decide it. What separates them is feature set and interface, not measurable difference.

Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS

CostPrice · In-app purchases · Ads · Monetization

Both are free to download. Frontier X sells 2 in-app purchases, starting at $14.99 per month and Protocol sells 2 in-app purchases, starting at $39.99 per year. Whichever you choose, the download price is not the number that matters.

ScorecardNo meaningful differences
Frontier X versus Protocol: the parameters behind the verdict, then further details
ParameterFrontier XProtocol
PriceFreeFree
Rating4.6 (318 ratings) — better—
Positive reviews81.8% of reviews—
Number of ratings318 — better—
Update frequencyEvery 3 weeks—
AdsNoNo
In-app purchasesYesYes
MonetizationFree with in-app purchases—
DevicesiPhone, Apple WatchiPhone, iPod
Requires iOS16.015.1 — better
Further details — not scored
Size569 MB40 MB
Age rating4+17+
DeveloperFourthfrontierKevin Marsh

Bugs and requests

Frontier X

Reported bugs

4 issues
  • ECG stopped working
  • Inaccurate breathing rate and other metrics
  • Inability to edit activity details for indoor workouts
  • Syncing issues with Garmin devices after firmware updates

Requested features

6 requests
  • Add interval markers
  • Improve integration with Apple Fitness/Fitness+
  • Add support for ANT+
  • Improve compatibility with other fitness apps and devices
  • Add more customization options for workouts
Show 1 more
  • Improve data visualization and analysis tools

Protocol

Not enough reviews yet to summarise bugs or requests.

In-app purchases

2 purchases

Frontier X

Subscriptions2
  • Monthly7 Days trial$14.991 Month
  • Yearly7 Days trial$119.991 Year
2 purchases

Protocol

Subscriptions1
  • Annual7 Days trial$39.991 Year
One-time1
  • Lifetime$99.99

Questions

Is Frontier X free?
Frontier X is free to download, with in-app purchases available.
Is Protocol free?
Protocol is free to download, with in-app purchases available.
Do Frontier X or Protocol have ads?
Neither Frontier X nor Protocol shows ads.

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