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OpenTuner

A tuner that only tunes.

Pluck a string and OpenTuner tells you if it is loose, too tight or in tune. Ukulele, guitar, bass and their cousins. That's all it does.

Download for Android Google Play · coming soon

Free and open source · Android 7.0 or newer · iOS later

♭ ♯ E 4 ✓
How it works

Look at one line

The center line is the note. The marker shows how far the string is from it, in cents, and the trail below shows how you got there.

Left of the line

Loose

The string sounds lower than the note. Tighten it and the marker walks right.

On the line

In tune

Keep it there for a moment: a green ring closes around the marker, a chime plays and the string gets a green check. Move on to the next one.

Right of the line

Too tight

The string sounds higher than the note. Loosen it a little. Yellow means you are close.

All strings in tune? Start over clears the checks, to tune another instrument or check them all again.

Instruments

Standard tuning is already picked

Choose the instrument and the tuning from the bar at the bottom. On Auto, OpenTuner hears which string you played. Or tap a string to lock it and hear its note, synthesized by the app, to tune by ear.

Ukulele & cavaquinho

  • UkuleleStandardLow GD tuning
  • Baritone ukuleleStandard
  • CavaquinhoStandardNatural

Guitar & viola

  • GuitarStandardDrop DHalf step downWhole step downDADGADOpen GOpen D
  • 7-string guitarLow CLow B
  • Viola caipiraCebolão in ECebolão in DRio abaixo

Bass

  • 4-string bassStandardDrop DHalf step down
  • 5-string bassStandardHigh C
  • 6-string bassStandard

Bowed strings

  • Violin (beta)Standard
Settings

Set it your way

The settings open from the corner at the top of the screen. Your choices stay saved on your phone.

On screen

  • ThemeSystemLightDark
  • Note namesC D EDo Re Mi
  • LanguageSystem languageEnglishPortuguêsEspañol

While you tune

  • Reference A (A4)430 to 450 Hz
  • PrecisionNormal · ±5 centsFine · ±2 cents
  • Keep screen onOnly while the tuner is open

No ads. Not now, not later.

OpenTuner is simple on purpose: one screen, one job. There are no ads, no tracking, no account and nothing to buy inside the app.

My goal is to never show an ad, for as long as I can pay for this project and keep it in the store.

Guilherme Feitoza, author

  • No ads
  • No tracking
  • No account
  • No in-app purchases
Privacy and code

It only listens, and only while you tune

Microphone, and nothing else

The microphone is the only permission OpenTuner asks for. Sound is analyzed in memory as you play and thrown away. It is never recorded, and the app has no internet permission, so it could not send anything even if it wanted to. It works offline, always.

Read the privacy policy

Open source

The whole app is on GitHub under the Apache 2.0 license. Read it, build it yourself, report a bug, or help translate it into your language.

github.com/guilhermefeitosa66/open-tuner

Download

Install it from GitHub

Each version is published on GitHub Releases as APK files, for Android 7.0 or newer. Google Play is coming soon.

Which file to pick

  • arm64-v8aMost phones
  • armeabi-v7aOlder 32-bit ARM phones
  • x86_64Chromebooks and emulators

The architecture is at the end of the file name. The first time, Android may ask you to allow installing apps from your browser or file manager.

Latest release

Check what you downloaded

The SHA-256 checksums of the APKs are in SHA256SUMS.txt, in the same release. Every APK is signed with the same certificate, and this is its SHA-256 fingerprint, the same in every version:

b8b7f73d8b7444f478f2ee19a7d3df61798d86a465b4b0dd5acf69bc9408834f