Centerline

Centerline is a chromatic tuner that identifies the note being played, indicates whether it is flat or sharp, and shows where the pitch settles. Chromatic mode covers 62–800 Hz and follows the nearest note, including sharps and flats. Four display choices are available: Simple, Trail, Strobe, and Workbench; Trail shows six seconds of pitch history. Guitar mode detects strings automatically or lets players select one, with standard tuning, All Strings progress, and a headstock view. Tuning works offline, and pitch analysis takes place on the device without recording, saving, transmitting, or sharing microphone audio. The free Chromatic plan includes the core tuner and guitar views. Centerline Complete costs $3.99, paid once and adds alternate and custom tunings, capo settings, A4 calibration from 432–446 Hz, and reference tones. The app has no ads or account system. Optional usage analytics are off until enabled and exclude audio and pitch data. It is available for Android, iOS, and macOS.

Centerline offers a free tuner with multiple displays and a focused guitar mode. The one-time Complete purchase adds tunings and reference options, while the stated range excludes some instruments’ lowest or highest notes.

Centerline suits musicians who want an offline tuner with chromatic and guitar-specific views. Its stated frequency range and tuning limits may matter to players of piano or low-register bass.

Overview

Centerline is a chromatic tuner for players who want a clear pitch reading, with a dedicated set of tools for guitar. Its strongest fit is someone tuning at home or on the go who values offline use and on-device audio processing.

The free version covers the core tuning workflow; the one-time upgrade is most useful if you need alternate or custom guitar tunings, capo settings, or reference tones. Players tuning a full-range piano or the lowest notes of a bass should look elsewhere.

Key features

Multiple ways to read pitch

Chromatic mode follows the nearest note, including sharps and flats, from 62–800 Hz. Simple, Trail, Strobe, and Workbench views let users choose how to read that pitch; Trail retains six seconds of pitch history. The range suits many instruments and tuning needs, but its limits at the low and high ends rule out full piano coverage and a bass guitar’s lowest notes.

Purpose-built guitar mode

Guitar mode offers automatic string detection or direct string selection, along with standard tuning, an All Strings progress view, and a headstock view. All Strings remembers individual readings as you move across the instrument, but it does not assess a chord at once. That makes it a useful guide for tuning strings individually, not a shortcut for checking a strummed chord.

Privacy and offline use

Tuning works offline, without ads or a Centerline account. Pitch analysis runs on the device, and microphone audio is not recorded, saved, transmitted, or shared. Usage analytics are off by default; if enabled, they exclude audio and pitch data. The optional unlock is handled as a one-time store purchase, without an account or payment-card details going to the app.

Pricing

The free plan is sufficient for standard chromatic tuning and the included guitar workflow. Complete is a focused upgrade for guitarists who regularly change tunings or want to adjust reference pitch; it is a one-time purchase, with no trial or recurring charge. Those who do not need its added tuning and reference options can stay on the free plan without giving up the core tuner.

Platforms

Centerline is available for Android, iPhone, and Mac. The App Store listing specifies iPhone and Mac availability, while the maker’s site links to Android and iPhone downloads.

Who it's for

Centerline makes sense for guitarists who want both a general chromatic tuner and a guitar-specific workflow, especially if they value offline operation and keeping pitch analysis on-device. It is less suited to players who need the extreme low or high ends of an instrument’s range, or who expect All Strings to evaluate a chord in one pass.

Pros and cons

• Pros: The free version includes four chromatic displays and a dedicated guitar mode, giving users several ways to tune without paying.
• Pros: Offline tuning, no ads or account requirement, and on-device pitch analysis suit users who want a private, dependable tuner away from a connection.
• Pros: Complete adds alternate and custom six-string tunings, capo settings, calibration, and reference tones for a single purchase.
• Cons: The 62–800 Hz range misses the lowest bass notes and does not cover a piano’s full range.
• Cons: All Strings tracks individual readings rather than measuring a chord at once, so it does not replace a chord-level check.

Alternatives

Musical Tuner Apps is a useful starting point for comparing more tuners. ChromTuner is worth considering if you want a free browser tuner with an LED meter as well as iPhone and Mac options. DaTuner is an Android-only alternative with a free, ad-supported tier and a Premium option that removes ads and adds features; it also offers a free trial.

Fender Tune is another free Android and iOS tuner, with Tune Plus requiring a Fender account. GuitarTuner.io is a free web tuner for people who prefer to tune in a browser without an account or paid upgrade. insTuner may suit iPhone and Mac users seeking a free tier with Instant-Tuning Mode and a tone generator.

n-Track Tuner offers Android and iOS versions, with a free version and a $2.99, paid once Pro version. Pano Tuner is an alternative if you want tuning features and temperaments on Android for free with ads, or a paid iOS app. Pitched Tuner is another Android and iOS choice; its Pro upgrade enables creating and saving custom tunings and temperaments.

Verdict

Choose Centerline if you want a no-cost chromatic tuner with a dedicated guitar workflow, offline use, and on-device pitch analysis, and pay for Complete only if its alternate tunings, capo controls, or reference options matter to your setup. Look elsewhere if your instrument needs pitches beyond 62–800 Hz or you need a tuner that measures a chord as a whole.