Centerline

Overview

The chromatic tuner identifies the nearest note, including sharps and flats, and shows whether the pitch is flat or sharp and where it settles. Its 62–800 Hz range suits many instruments and common tuning needs, but leaves out the full piano range and a bass guitar’s lowest notes. Players who need those extremes should choose a tuner with a wider range.

Centerline works offline and has no ads or account system. Pitch analysis stays on the device: microphone audio is not recorded, saved, transmitted, or shared. Usage analytics are off unless enabled, and exclude audio and pitch data when enabled. The result is a good fit for musicians who prefer a tuner that does not rely on a connection or account.

Key features

Chromatic views

Simple, Trail, Strobe, and Workbench views give users different ways to read pitch. Trail shows six seconds of pitch history, useful for seeing how a note settles rather than relying only on a single reading. Strobe display is included, and intonation monitoring is supported.

Guitar mode

Guitar mode detects strings automatically or lets players select a string directly. Standard tuning, an All Strings progress view, and a headstock view support both quick single-string checks and working through a guitar. All Strings remembers individual readings, but does not measure a chord at once; players seeking a chord-level reading should look elsewhere.

Alternate tunings and calibration

Centerline Complete adds Drop D, Half step down, D standard, DADGAD, and Open G, as well as custom six-string tunings and capo settings. It also adds A4 calibration from 432–446 Hz and reference tones. Those controls make the upgrade more useful for players who change tunings or want to adjust their reference pitch; standard tuning users can stay with the free tier.

Pricing

Centerline is freemium, with no free trial and no recurring charge. The optional unlock is a one-time store purchase; payment is handled through the store, and the app does not receive card details or require an account.

The free plan includes the core tuner and guitar workflow rather than imposing a recurring fee or trial deadline. It gives up the alternate tunings, custom tuning setup, capo settings, calibration, and reference tones in Complete.

Platforms

Centerline is available for Android, iOS, and macOS. The App Store listing specifies iPhone and Mac availability; the maker’s site links to Android and iPhone downloads. Offline tuning means musicians can use it without an internet connection.

Who it's for

Centerline suits musicians who want a no-account, ad-free tuner for routine chromatic work, and guitarists who want string detection and progress tracking. The free plan is a sensible stopping point for standard tuning. Guitarists who regularly use alternate tunings can justify the one-time Complete purchase, while pianists needing the full instrument range and bassists tuning the lowest strings should choose a tuner with broader frequency coverage.

Pros and cons

• Pros: Offline tuning and on-device audio analysis make it practical without a connection and keep microphone audio from being recorded or shared.
• Pros: Four chromatic views, including a six-second Trail history and Strobe display, offer more than a single pitch readout.
• Pros: Guitar mode combines automatic and direct string selection with an All Strings workflow and headstock view.
• Pros: Complete is a one-time purchase, with custom six-string tunings, capo settings, calibration, and reference tones for players who need them.
• Cons: The 62–800 Hz range excludes the full piano range and a bass guitar’s lowest notes.
• Cons: All Strings tracks individual readings rather than measuring a chord simultaneously.
• Cons: Alternate tunings and other advanced guitar controls require the paid unlock.

Alternatives

Musical Tuner Apps is a broader place to compare tuner choices. For a free browser option, GuitarTuner.io offers a web tuner without an account or paid upgrade and also supports Android, iOS, macOS, and Windows.

ChromTuner is another freemium choice, with a free browser chromatic tuner, LED meter, and browser microphone input, as well as a free iPhone app. Bandmate Chromatic Tuner is free across Android, iOS, and web, with no third-party ads.

Fender Tune is worth considering for a free Android or iOS tuner; its Tune Plus requires a Fender account. JustATuner is a free alternative for Linux, macOS, and Windows.

n-Track Tuner offers a free Android and iOS version and a 2.99 USD per once Pro version. Nembrini Audio Chromatic Tuner is free for iOS, macOS, and Windows and supports VST2, VST3, AAX, or AudioUnits hosts. Pano Tuner is another Android and iOS option, with an ad-supported free Android app and a 3.99 USD per once iOS app.

Verdict

Choose Centerline if you want dependable everyday chromatic or standard guitar tuning with offline use, no account, and on-device audio analysis. Guitarists who need alternate tunings or calibration get a clear upgrade path through a one-time purchase. Look elsewhere if you need piano-wide or very low bass coverage, or chord measurement in one pass.