OpenTuner: String Tuner

Ukulele, guitar & bass tuner

Only for iPhone

Free · Designed for iPhone. Not verified for macOS.

iPhone

Simple tuner for ukulele, guitar and bass. Free, with no ads, and works offline. OpenTuner is a string tuner that only tunes. Pluck a string and it tells you if the string is loose, too tight or in tune. HOW TO READ IT • Left of the center line: the string is loose. Tighten it. • Right of the line: it is too tight. Loosen it. • On the line: in tune. A green ring closes around the marker, a chime plays, and the string gets a green check. The trail below the marker scrolls down and shows how you got there. INSTRUMENTS • Ukulele: standard, low G, D tuning • Baritone ukulele • Cavaquinho: standard, natural • Guitar: standard, drop D, half step down, whole step down, DADGAD, open G, open D • 7-string guitar: low C, low B • Viola caipira: cebolão in E, cebolão in D, rio abaixo • 4, 5 and 6-string bass • Violin (beta) Standard tuning is already picked. OpenTuner hears which string you played, or you can tap a string to lock it. SIMPLE ON PURPOSE • No ads. Not now, not later. • No account, no tracking, no in-app purchases. • Only one permission: the microphone. Sound is analyzed on your phone and never recorded. • No internet permission, so it works anywhere, offline. • Light and dark themes, C D E or Do Re Mi note names, adjustable reference pitch (A4). OPEN SOURCE OpenTuner is free and open source under the Apache 2.0 license. The code is on GitHub: github.com/guilhermefeitosa66/open-tuner

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The developer, Guilherme Feitoza de Sousa Lima, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .

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    Information

    Seller
    Guilherme Feitoza de Sousa Lima
    Size
    18.3 MB
    Category
    Music
    Compatibility
    Requires iOS 15.0 or later.
    • iPhone
      Requires iOS 15.0 or later.
    • iPod touch
      Requires iOS 15.0 or later.
    • Mac
      Requires macOS 12.0 or later and a Mac with Apple M1 chip or later.
    Languages
    English and 2 more
    • English, Portuguese, Spanish
    Age Rating
    4+
    Copyright
    © 2026 Guilherme Feitoza
  • Developer Website
  • Privacy Policy