Centerline vs SonoSpec
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Centerline
This app offers free chromatic tuning for various instruments, identifying notes, sharps, and flats. It includes a dedicated guitar mode with automatic string detection and optional advanced tuning tools for purchase.
- Free chromatic tuning
- Dedicated guitar mode
- Automatic string detection
- Pitch history tracking
- Offline functionality
- No ads or accounts
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Tune the note you play. Play one note and see its name, whether it is flat or sharp, and where it settles. Centerline gives musicians free chromatic tuning from 62 to 800 Hz, plus a dedicated six-string Guitar mode. CHROMATIC TUNING, FREE Chromatic mode follows the nearest note, including sharps and flats. Use Simple for a clear direction, Trail to follow your pitch history, Strobe for fine adjustments, or Workbench for cents and frequency. All four views are free. WHAT YOU CAN TUNE Chromatic mode names any note from 62 to 800 Hz. That covers guitar, ukulele, violin, viola, mandolin and banjo in standard tuning, and most voices. Band instruments work at their concert tuning note. A DEDICATED GUITAR MODE Guitar mode adds automatic string detection and direct string selection. Standard tuning is free. All strings keeps track of the strings you have played. Guitar shows each string as a button: tap one to lock it, or let Auto follow the string you play. All six Guitar views are free. YOUR PREFERRED VIEW Simple is your starting view. Trail shows six seconds of pitch history and can rotate between vertical and horizontal. Centerline remembers your preferred view in each mode. OPTIONAL EXTRA TUNING TOOLS Centerline Complete is a one-time purchase for Drop D, Half step down, D standard, DADGAD, Open G, custom six-string tunings, capo settings, A4 calibration from 432 to 446 Hz, and reference tones. No subscription. Restore Purchase is available in the app. The store shows your local price. PRIVATE BY DESIGN Pitch analysis happens on your device. Centerline does not record or upload your audio. There are no ads or accounts. Optional usage analytics are off until you allow them and never include audio or pitch data. Tuning works offline. Play one note or string at a time. All strings remembers individual readings; it does not measure a chord at once. Chromatic mode supports 62 to 800 Hz and does not cover the full piano range or a bass guitar's lowest notes. Questions or feedback: wyatt@endpaperlabs.com Privacy: https://centerlinetuner.com/privacy
SonoSpec
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SonoSpec turns your iPhone or iPad microphone into a beautiful real-time audio spectrum analyzer. Built for car-audio tuning, room acoustics, HVAC and machinery noise hunting, speaker testing, and anyone who wants to SEE what they're hearing. FOUR VIEWS, ONE INSTRUMENT • Spectrum — live FFT trace with peak hold and a log-frequency grid • Waterfall — scrolling spectrogram that makes tones, sweeps and rattles obvious • Split — spectrum and waterfall together • Octave — 31-band 1/3-octave RTA bars MEASUREMENT-GRADE DETAILS • FFT sizes from 2,048 to 16,384 points (5.9 Hz resolution at 48 kHz) • A, C and Z weighting curves computed per the IEC 61672 formulas • Exact base-10 1/3-octave bands per the IEC 61260 definitions • Peak-hold trace with slow decay, pause/hold, and a drag cursor that reads out the exact frequency and level under your finger • Levels in dBFS with a proper full-scale sine reference and window-bandwidth (ENBW) correction — the numbers mean something BUILT-IN SIGNAL GENERATOR • Pink noise, white noise, sine, log sweep and warble tones — the source half of the RTA workflow • Feed the system under test by cable or USB and watch the response live TARGET CURVES • Overlay a house curve — flat, −3 dB/oct tilt, or a bass-lifted car target — on the live spectrum • Auto-fit positioning: the shape snaps to your measurement, no fiddling SNAPSHOTS & EXPORT • Freeze a measurement and recall it as a ghost overlay for before/after comparison • Share a publication-ready image or CSV with a full metadata header — FFT size, window, weighting — so your data still means something later TUNED TO FEEL LIKE HARDWARE Rendering runs on a dedicated Metal graphics path at the full analysis rate, with a phosphor-and-ember instrument look that's readable at arm's length. On iPad it fills the screen and adapts to Split View and Stage Manager windows. PRIVATE BY CONSTRUCTION Audio is analyzed on-device and never recorded, stored, or transmitted. SonoSpec has no accounts, no ads, no analytics — the app cannot even access the network. One-time purchase. No subscriptions.
Screenshots
Verdict
The clearest difference is price: Centerline at Free against SonoSpec's $9.99. Centerline also leads on update cadence (every 5 days vs every 2 months). SonoSpec's advantage is in-app purchases (none vs 1). On ads, device support and iOS requirement 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
Centerline is free to download; SonoSpec costs $9.99 up front. Centerline sells 1 one-off in-app purchase. SonoSpec asks for nothing beyond the download.
Centerline ships an update every 5 days, SonoSpec every 2 months. The most recent releases landed on November 6, 2026 and November 8, 2026 respectively.
| Parameter | Centerline | SonoSpec |
|---|---|---|
| Price | Free — better | $9.99 |
| Rating | 5.0 (4 ratings) — better | — |
| Number of ratings | 4 — better | — |
| Update frequency | Every 5 days — better | Every 2 months |
| Ads | No | No |
| In-app purchases | Yes | No — better |
| Monetization | Free with in-app purchases | — |
| Devices | iPhone, Mac | iPhone, iPad |
| Requires iOS | 17.0 | 17.0 |
| Further details — not scored | ||
| Size | 3 MB | 1 MB |
| Age rating | 4+ | 4+ |
| Developer | Endpaper Labs LLC | Corey Thomas Slick |
In-app purchases
Centerline
- Centerline Complete$3.99
SonoSpec
No in-app purchases









