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String Tension AI

String Tension AI

Measure Racquet Tension

2 ratings
5 reviews
🔧 Utilities
⚽ Sports
Free
In-App Purchases

Details

  • Released
  • Updated
  • May 3, 2026
  • September 27, 2026

Features

Developer

Trader Prosperity LLC
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🧾$69.99
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❓8 answered
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About

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.

✓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
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What's New in String Tension AI

2.32

September 27, 2026

String Tension AI 2.32 gives users of the #1 iOS tennis racquet and string-tension tracking app a narrated How to Measure video with localized captions, more accurate string-job history, and clearer spending by currency. Apple Health import review remains free on supported devices, while automatic import remains a PRO feature. The Tension Advisor now keeps recommendations consistent across restrings; personalized advice continues to require PRO. Calibration and tension forecasts handle changes in the calibration used for a set of strings, and Apple Health sessions that may duplicate a manual log are easier to review. Exports, reminders, purchase restore, recovery and iCloud sync are more reliable. Existing data is preserved during a normal upgrade; the release includes a lightweight local data migration and already deployed iCloud schema additions. Optional diagnostics continue to respect analytics consent. App Store Release Notes - Learn to measure with the narrated How to Measure video, localized captions, playback controls and Skip. - Past string jobs imported from Apple Health stay in history without replacing current strings; backdated restrings assign playing sessions to the strings used on those days. - Tension Advisor recommendations no longer drift just because you followed earlier advice and restrung again. Split-tension setups apply the suggested change to both sides. - Calibration and forecasts use readings from the current calibration; older strings ask you to enter a current reference tension. - Spending and comparisons keep different currencies separate. Cost per day uses completed string jobs with recorded prices. - Possible duplicate Apple Health sessions are flagged for review, and automatic import resumes more reliably after PRO is renewed. - CSV and PDF reports are easier to use, with clearer split tensions, improved racquet QR links and better spreadsheet compatibility. - Restore Purchases shows progress and a clear result. Reminders, backups and iCloud sync are more reliable, and measuring stays responsive while the microphone starts.

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Subscriptions & In-App Purchases

Annual PRO

Best value — Save 50% vs monthly

$29.991 Year
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User reviews

Most RecentHighest RatedLowest Rated

Much Improved

When I originally tried the app, I had issues getting it to work. Since the update, there have been no issues. The interface is intuitive and well thought out. It allows you to enter key data about the strings and your setup. I have tried just about every tennis string tension app available, and String Tension AI has the best interface and excellent performance. String Tension AI is now my go to app to measure and track the tension of my string bed.
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Teufelhunden0352Teufelhunden0352

Response from developer

We’re sorry you had this experience. We take performance reports seriously and continuously improve String Tension AI with frequent updates, extensive diagnostics, and 10,000+ automated tests. Apple’s Xcode reports show zero hangs across our last five releases, and our independent crash monitoring has likewise shown no recent widespread crash or freeze issues. We also continue optimizing performance for older devices. If you’re using an iPhone 12 or older, please install the latest version, which includes additional compatibility and performance improvements. String Tension AI is actively developed and is consistently updated with new features and reliability improvements on a regular basis. If you experience any issue, please contact us through the app or at stringtensionai.com so we can investigate it directly and help. We're always happy to help. Thank you, String Tension AI Team

Much Improved

After having a disappointing first use, and following a developer response, I gave the app another try. I have to say I was very impressed with the app. The layout is very intuitive, allows for excellent customization and entry of details. The developers, through their response to my concerns, have shown a strong desire to produce an excellent app that is both useful, but also very functional. I used it on an iPhone 11, and had no issues. Sting Tension AI is now my go to app to track the tension of my strings.
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Teufelhunden0352Teufelhunden0352

General usability and effectiveness

Love using the app. Has really helped me understand the best string type/tension for my specific racquet and play style and would definitely recommend. Looking forward to using it every time my string breaks 😂.
rgame99rgame99

Freezes

Unfortunately, I never got to the point where I could test if this app can actually test my racket string bed tension. It requires you to set up the racket and string setup. It constantly froze. I finally gave up and deleted the app.
Teufelhunden0352Teufelhunden0352

Great for tracking string tension over time

I’ve been using this for one month now and it's become part of my routine before matches. You just tap the strings and get a reading. What surprised me is how consistent the readings are when I tracked them over time. I like the chart readings and trends. I use Luxilon Alu Power and those strings lose tension fast, so being able to actually see the drop over a week or two is really useful for knowing when my strings are dead and impacting my game. After getting my racquet restrung I calibrated it in the app and the absolute tension numbers lined up pretty well too. There's also a section where you can see what strings and racquets the pros use which is fun to browse. Can't believe this is free honestly. Wish I found it earlier.
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RogerFederer07RogerFederer07

FAQ

How does String Tension AI measure string tension?

String Tension AI uses your iPhone's microphone to analyze the sound produced when you tap your racquet strings. The app then processes this sound to calculate the current tension of your strings.

What are the benefits of the Pro version of String Tension AI?

The Pro version unlocks advanced features like full analytics and decay charts, a tension advisor, string recommendations, hybrid string builder, cost analytics, detailed playing stats, milestones, iCloud sync, and PDF/CSV export.

Can I use String Tension AI on multiple devices?

Yes, with the Pro version, iCloud sync is available, allowing you to keep your data across all your devices seamlessly.

How often is String Tension AI updated?

The app was last updated on 2026-06-22, indicating regular updates to improve features and reliability. The latest version is 2.13.

What is the age rating for String Tension AI?

String Tension AI has an age rating of 4+, making it suitable for a wide range of users.

Does String Tension AI have ads?

No, String Tension AI does not contain advertisements. The app is ad-free.

What kind of reports can I export from String Tension AI?

With the Pro version, you can export detailed PDF and CSV reports. You can also send string job reports directly to your stringer.

How does String Tension AI compare to a physical string tension meter?

String Tension AI offers the convenience of using your iPhone's microphone, eliminating the need for external devices. It also provides advanced tracking, analysis, and personalized recommendations that physical meters may not offer.