Comparison

Ski Lines vs String Tension AI

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

Head to head
About

Ski Lines

Track your altitude, distance, speed, and turns during sports activities. It uses GPS and maps for offline access, allowing you to review your progress and stats anytime. This tool can help improve your performance and retrace your routes.

Highlights
  • Record altitude, distance, speed, and turns
  • Background recording with progress view
  • Offline map access (Google Maps, Open-street-maps)
  • View live speed and altitude
  • Capture run duration, G-Force, and turns
  • Manage and share data across devices
Read full description

Take your sport activities to the next level. Click on the Record button, and your altitude, distance, speed, and even the number of turns, for every run, will be captured for the entire day. Recording takes place in the background, but you can view your progress anytime. It uses Google maps as well as Open-street-maps for offline access, when you don’t have an internet connection. You can view your stats and your location on the map throughout the day. On the Dashboard screen, you can view your live speed and altitude. A run can be captured to show duration, number of turns, average, and maximum G-Force associated with your turns. This can be your coach to improve your dynamic turns! The app is optimized for skiing and riding, but it is also useful for hiking, walking, and driving. Let’s say you visited a ski resort and a guide showed you around the mountain. Later on, you can use this app to find that fun run the guide took you on around 2:00pm. At any time, you can see how long did you wait in the lift line, or how long did you get stuck in the freeway traffic. Key features: -Relies on GPS for accurate location, speed, and direction. -Has a minimum impact on battery consumption, and only during recording. -Available on most mobile devices, Windows PC, and MacOS. -Intuitive & easy to use utility to manage/share your data among devices, and friends. -View the capture on the mobile device, or the big screen of a Windows PC, or a Mac. -Does not collect, share, or transmit any user information. -No adds, no on-line purchases, and no log-in required.

About

String Tension AI

This app uses your iPhone's microphone to measure the tension of your racquet strings. It tracks tension decay over time, offers personalized restring recommendations, and provides a comprehensive string toolkit for serious players.

Highlights
  • Measure string tension with iPhone microphone
  • Track tension decay over time
  • Personalized restring recommendations
  • String database and player setups
  • Playing session tracking
  • Cost tracking for restringing
Features
Read full description

Measure tennis string tension. Make your next restring count. String Tension AI is an iPhone app for measuring tennis string tension, tracking tension loss and choosing when to restring. Tap your racquet's stringbed near the microphone to get a tension estimate in kg or lb. No external hardware needed. AVAILABLE IN 8 LANGUAGES English, German, French, Italian, Spanish, Brazilian Portuguese, Simplified Chinese and Danish. The app follows your iPhone's language, with regional dates, numbers and currency. Choose a different app language in iOS Settings. MEASURE AND TRACK FOR FREE • Take unlimited measurements for one racquet and review your 20 most recent readings. • Get live quality coaching, cross-checks across multiple taps and calibration against a known reference tension. Readings that do not hold up are set aside from guidance. • Follow How to Measure with narration and captions in all eight languages. • Check String Health, tension trends and restring guidance based on usable readings. • Track full beds, hybrids, custom strings and separate main/cross tensions. CONNECT YOUR PLAYING AND STRING HISTORY • Log session duration, intensity and racquet; review the calendar, set goals, build streaks and celebrate milestones. • Review and import tennis workouts from Apple Health for free, with possible duplicates flagged. Optional heart-rate access can suggest intensity without saving heart-rate data. • Open My Stringers from the Strings hub to manage contacts, favorites, archives and restring history for free. • Browse expanded racquet and string catalogs and ATP, WTA and Legends setups. Save favorite strings, add ratings and discover daily tennis facts. • Share visual cards for supported string-health, tension, string-job and achievement highlights. GO FURTHER WITH PRO • Unlimited racquets and string setups, full measurement history and Measurement Insights. • Advanced tension-decay analytics; compare racquets, strings and completed string jobs. • Personalized string and hybrid recommendations using your playstyle, ratings and eligible retention history. • Tension Advisor with What If scenarios for your equipment, game and conditions. • Tension targets, optional alerts and Smart Detection for likely fresh strings or unusual tension changes. • Playing-hours restring forecasts when enough dependable data is available. • Automatic Apple Health import, detailed playing stats, advanced milestone tools and reminders. • Cost Analytics, cost per playing hour, annual budgets, wishlist and stringer Annual Summary with PDF export. • iCloud sync and PDF/CSV reports, including string-job reports for your stringer. ASK STRING AI COACH Ask about your racquet, tension, strings, playing history, restring timing and costs using your saved data. Questions, answers and racquet data stay on device. Available when the app is set to English, on compatible Apple Intelligence devices with iOS 26 or later, a supported system language and an available on-device model. Some questions require PRO. READY WHEN YOU ARE Check String Status widgets on your Home or Lock Screen. Use Siri, Shortcuts, Spotlight or the Action button to reach supported actions. Import, inspect and restore backups. Measurement audio is processed on device and never saved or uploaded; imported Health session records stay on your iPhone, outside iCloud sync and session exports. Shared summaries may include their totals. Optional analytics require consent. Enjoy smoother measuring, browsing and sharing, more reliable history, forecasts, reports and sync, plus VoiceOver, Dynamic Type and Reduce Motion support. Requires iOS 17 or later. Download free. Learn from every session. Restring with confidence. Terms of Use: https://stringtensionai.com/terms/ Privacy Policy: https://stringtensionai.com/privacy/

Screenshots

Ski Lines4 screens
String Tension AI4 screens

Verdict

The call

The clearest difference is in-app purchases: Ski Lines at none against String Tension AI's 3. Ski Lines also leads on review sentiment (100% vs 80%) and device support (4 vs 1). String Tension AI's advantage is update cadence (every 4 days vs every 18 months) and ratings volume (3 vs 1). On price, rating 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

CostPrice · In-app purchases · Ads · Monetization

Both are free to download. String Tension AI sells 3 in-app purchases, starting at $4.99 per month. Ski Lines asks for nothing beyond the download.

ReceptionRating · Positive reviews · Number of ratings

On the App Store both sit at effectively the same score — 5.0 for Ski Lines against 5.0 for String Tension AI. Both are backed by a comparable volume of ratings — 1 and 3 respectively. Written reviews are what separate them: 100% of Ski Lines's written reviews are positive against 80% of String Tension AI's.

UpkeepUpdate frequency

Ski Lines ships an update every 18 months, String Tension AI every 4 days. The most recent releases landed on October 1, 2026 and October 14, 2026 respectively.

Scorecard7 real differences · 3 level
Ski Lines versus String Tension AI: the parameters behind the verdict, then further details
ParameterSki LinesString Tension AI
PriceFreeFree
Rating5.0 (1 ratings)5.0 (3 ratings)
Positive reviews100.0% of reviews — better80.0% of reviews
Number of ratings13 — better
Update frequencyEvery 18 monthsEvery 4 days — better
AdsNoNo
In-app purchasesNo — betterYes
MonetizationFree — betterFreemium
DevicesiPhone, iPad, iPod, Mac — betteriPhone
Requires iOS13.0 — better17.0
Further details — not scored
Size21 MB83 MB
Age rating4+4+
DeveloperHaz NabulsiTrader Prosperity LLC

Customer experience

Ski Lines

All ratings1 ratings
Positive100.0%
Neutral0.0%
Negative0.0%
Written reviews2 reviews
Positive100.0%
Neutral0.0%
Negative0.0%

String Tension AI

All ratings3 ratings
Positive100.0%
Neutral0.0%
Negative0.0%
Written reviews5 reviews
Positive80.0%
Neutral0.0%
Negative20.0%

In-app purchases

None

Ski Lines

No in-app purchases

3 purchases

String Tension AI

Subscriptions2
  • Monthly PRO$4.991 Month
  • Annual PRO$29.991 Year
One-time1
  • Lifetime PRO$69.99

Questions

Is Ski Lines free?
Ski Lines is free to download, with no in-app purchases.
Is String Tension AI free?
String Tension AI is free to download, with in-app purchases available.
Which has better reviews, Ski Lines or String Tension AI?
Ski Lines and String Tension AI are both rated 5.0 out of 5 on the App Store, from 1 and 3 ratings respectively.
Do Ski Lines or String Tension AI have ads?
Neither Ski Lines nor String Tension AI shows ads.
Which is updated more often, Ski Lines or String Tension AI?
Ski Lines ships an update every 18 months, and String Tension AI every 4 days. Most recently, Ski Lines was updated on October 1, 2026 and String Tension AI on October 14, 2026.

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