String Master vs String Tension AI
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
String Master
Optimize your tennis game by precisely tracking string tension and durability. Record every restring, analyze string performance, and discover the best setups for your playstyle. Never guess about your strings again.
- Smart Restring logging
- Custom string input
- Smart String Finder
- Restring reminders
- Detailed logs and history
- Hybrid setup support
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Stop guessing, start tracking. String Master is the ultimate performance-tracking companion for tennis players who demand the best from their equipment. Whether you are a casual player or a competitive athlete, your string setup dictates your game. String Master helps you record, analyze, and discover the perfect string configurations tailored to your unique playing style. [Major New Updates & Premium Features] • Smart Recommendation Wizard & Normalized Engine Finding your next string is now effortless. Our 3-step recommendation wizard uses lab-tested data (stiffness, spin potential, tension loss, energy return) and scales them using min-max normalization to prescribe the perfect setup matching your game. • Dynamic Activity Calendar & Backdating Visualize your active string health on a color-coded calendar. Log past sessions, backfill older stringing jobs, and edit durations with instant, automatic health percentage recalculations. • Playability & Environmental Logging Go beyond time tracking. Log how your strings feel (Soft, Crisp, Stiff, or Dead Poly), track weather conditions (Sunny, Humid, Cloudy), and record temperatures to understand how environment impacts your tension. • Community Insights & Lifespan Rankings Access real-time community statistics and trends. View the top average string lifespan rankings based on thousands of hours of real player data. (Access is granted to active members with a minimum of 4 hours of logged play over the past 14 days.) • Advanced Racket Specifications Track customized parameters for every racket in your bag. Log weight (g), stiffness (ra), swing weight (kg/cm²), balance point (mm), serial numbers, and custom tuning notes (lead tape, grip details). • Smart Restring & Terminology Polish Log a new job in 3 seconds! Tap "Restring" to clone your previous setup (racket, string, tension). Terminology has been audited and standardized to "History" across 10 languages. • Social Authentication & Data Migration Log in instantly with Google or Apple Sign-In. Seamlessly migrate your entire guest mode racket and stringing history to your permanent account in one click. [Core Features] • Restring Reminders: Set custom notifications (90 days or health below 20%) to prevent arm strain and maintain peak playability. • Hybrid Setup Support: Independently log mains and crosses (different brands, gauges, and tensions). • 10-Language Expert Guides: Tap the info (i) icons to read explanations of string materials and metrics, fully localized in 10 languages (EN, KO, ES, JA, ZH, ZH_Hant, DE, FR, IT, PT).
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.
- 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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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 streaks and goals, celebrate milestone unlocks and rank-ups, and share milestone cards. PRO adds the gallery, nudges, and alerts. • 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, advanced milestone features, wishlist and stringer tools, advanced String AI Coach questions, iCloud sync, and PDF/CSV export. Measure today. Learn from every session. Restring with confidence. Terms of Use: https://stringtensionai.com/terms/ Privacy Policy: https://stringtensionai.com/privacy/
Screenshots
Verdict
The clearest difference is in-app purchases: String Master at none against String Tension AI's 3. String Master also leads on ratings volume (7 vs 2) and iOS requirement (15.6 vs 17.0). On price, rating, update cadence 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
Both are free to download. String Tension AI sells 3 in-app purchases, starting at $4.99 per month. String Master asks for nothing beyond the download.
On the App Store both sit at effectively the same score — 5.0 for String Master against 5.0 for String Tension AI. Both are backed by a comparable volume of ratings — 7 and 2 respectively.
String Master ships an update weekly, String Tension AI every 5 days. The most recent releases landed on September 14, 2026 and September 23, 2026 respectively.
| Parameter | String Master | String Tension AI |
|---|---|---|
| Price | Free | Free |
| Rating | 5.0 (7 ratings) | 5.0 (2 ratings) |
| Positive reviews | — | 66.7% of reviews |
| Number of ratings | 7 — better | 2 |
| Update frequency | Weekly | Every 5 days — better |
| Ads | No | No |
| In-app purchases | No — better | Yes |
| Monetization | Free — better | Freemium |
| Devices | iPhone, iPod — better | iPhone |
| Requires iOS | 15.6 — better | 17.0 |
| Further details — not scored | ||
| Size | 71 MB | 33 MB |
| Age rating | 4+ | 4+ |
| Developer | ORYONG KIM | Trader Prosperity LLC |
Customer experience
String Master
String Tension AI
In-app purchases
String Master
No in-app purchases
String Tension AI
- Monthly PRO$4.991 Month
- Annual PRO$29.991 Year
- Lifetime PRO$69.99





