String Tension AI

Stop guessing. Start measuring. String Tension AI is the #1 tennis string tension measurement iOS app with most advanced algorithms. Tap your strings. Track tension loss.

Know when your strings are losing their edge, before you feel it on court.

String Tension AI turns a tap on your stringbed into a tension reading you can track. Use your iPhone's microphone to follow tension loss, understand each string job, and make better restringing decisions. No external hardware required.

MEASURE WITH CONFIDENCE

• Get a tension reading by tapping the center of your strings near your iPhone • Follow real-time quality coaching for clearer, more repeatable measurements • Calibrate against a known reference tension for a stronger baseline • Unlock PRO Measurement Insights that help improve your technique • Audio is processed on your device and is never recorded, stored, or uploaded

KNOW WHEN IT IS TIME TO RESTRING

• See String Health at a glance: Fresh, Good, Fading, or Restring soon • Follow tension-decay charts and the readings behind them • Get smart restring guidance based on your own trustworthy measurement history • With PRO, set tension targets and optional alerts when your strings move outside range • With PRO, let Smart Detection recognize likely fresh strings or unusual tension changes

LEARN WHAT WORKS FOR YOUR GAME

• With PRO, compare racquets, strings, and completed string jobs side by side • Analyze tension retention across multiple string jobs with PRO—not just the latest one • Use PRO Tension Advisor to explore a better tension for your equipment, game, and conditions • Get PRO string and hybrid recommendations matched to your playstyle, ratings, and qualified tension-retention history • Build and track full beds, hybrids, custom string models, and two-sided setups

ASK STRING AI COACH

On compatible devices, String AI Coach answers questions about your racquet, strings, tension, playing history, restring timing, and costs using your saved data. It runs with Apple's on-device model; your questions, answers, and racquet data are not uploaded. Requires iOS 26 or later, a supported locale, and an available on-device model. Some questions require PRO.

CONNECT PLAYING TIME TO STRING LIFE

• Log sessions with duration, racquet, and intensity • Review your month on a Playing Sessions calendar, including restring days • Build weekly streaks and goals; unlock 38 milestones with PRO • With PRO, see how playing volume affects tension retention and cost per playing hour

YOUR COMPLETE RACQUET AND STRING TOOLKIT

• Explore detailed string and racquet catalogs plus ATP, WTA, and Legends setups • Save favorite strings and rate what you have played; build a wishlist with PRO • With PRO, track stringers, restring costs, annual budgets, and retired setups • Create visual Share Cards for String Health, tension history, string jobs, milestones, streaks, and eligible cost insights • With PRO, export PDF and CSV reports, including string-job reports for your stringer • Import, inspect, and restore backups with clear safeguards • Keep PRO data in sync across your Apple devices with iCloud

Built for smooth performance with large histories, VoiceOver, Dynamic Type, and Reduce Motion.

FREE VS PRO

Free includes unlimited measurements for one racquet, your 20 most recent readings, quality coaching, calibration, String Health, session logging, goals, daily measurement tips, supported Share Cards, supported String AI Coach questions, and the string, racquet, and pro-player databases.

PRO unlocks unlimited racquets and string setups, full measurement history, advanced decay and comparison analytics, personalized string and hybrid recommendations, Tension Advisor, tension targets and advanced reminders, detailed playing and cost analytics, milestones, wishlist and stringer tools, advanced String AI Coach questions, iCloud sync, and PDF/CSV export.

Measure today. Learn from every session. Restring with confidence.

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