Comparison

Soi vs HarmonyAngel

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

Soi

Create and improvise music with others in real-time. This expressive instrument allows groups of any size to perform together, automatically harmonizing and synchronizing participants for an engaging experience where there are no wrong notes.

Highlights
  • Real-time music creation
  • Group improvisation
  • Automatic harmonization
  • Participant synchronization
  • Ensemble performance
Read full description

Become part of the magic of creation and improvisation. Join in with friends, family, or anyone and make music together. Soi is an expressive instrument that allows for a group of any size to perform as an ensemble. Soi automatically harmonises and synchronises each of the participants to help everyone to feel engaged. There are no wrong notes!

About

HarmonyAngel

Features
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HarmonyAngel is a MIDI and vocal harmony processor for musicians who want one monophonic line to follow the active chord. Choose chord slots on two performance pages, then play from a MIDI controller or the on-screen piano. For every incoming note, HarmonyAngel can generate descending chord tones below it, align voicings to a chord root, preserve slash-chord roots, and forward aftertouch to the generated harmony. Turn on Mic Input to sing into HarmonyAngel. The app performs low-latency monophonic pitch detection locally, uses the detected note to create the same chord-aware MIDI harmony, and provides a live tuner and input-level meter. Premium users can optionally hear pitch-corrected lead vocal and pitch-shifted vocal harmony audio, with selectable pitch detector, pitch shifter, formant, latency, buffer, trigger-level, and trigger-velocity controls. Choose a Jazz Soli style when you need arranged ensemble-style lines instead of simple chord stacking. Built-in Bebop, Smart Soli, Smooth Big Band, Functional Jazz, Barry Harris, Cool Jazz, Quartal Fusion, Minimal Guide Tones, and Altered Dominant styles use the active chord, melody direction, and musical register to produce practical voicings. Premium users can create, validate, import, export, and organize declarative custom styles in the Jazz Soli Library. Use it standalone with CoreMIDI and the built-in sine synth, or load the AUv3 MIDI processor inside a compatible host. Page controls, progression stepping, hold behavior, custom chord types, selectable MIDI ports, channel routing, keyboard range, display transpose, and velocity shaping are available from the performance UI. Highlights: - Two pages of 12 editable chord slots with no-harmony slots - Built-in chord types, slash roots, and named custom chord types - Jazz Soli styles for melody-aware, multi-part jazz voicings - Premium Jazz Soli Library authoring with validated import and export for custom styles - One-page or two-page MIDI control channel slot switching - Progression controls for stepping through saved chord sequences - Full or partial on-screen piano with touch velocity and aftertouch - Harmony count, root alignment, skip-first-harmony, and revoice-on-switch controls - Delta or ratio harmony velocity and aftertouch shaping - Mic Input with local monophonic vocal pitch detection, tuner, and input-level metering - Premium pitch-corrected lead vocal and pitch-shifted vocal harmony audio - Premium single-channel or rotating-channel harmony MIDI output - Premium MIDI input/output port selection and virtual MIDI output port - Hold and panic controls with process/bypass hold modes - Premium AUv3 MIDI processor extension with preservable host state - Optional built-in sine wave synth for quick testing or standalone use HarmonyAngel is designed for keyboardists, singers, composers, producers, worship musicians, live performers, and anyone who wants fast chord-aware harmony from simple MIDI or vocal input. Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/ Privacy Policy: https://bwinnovationtw.github.io/apps/harmonyangel/privacy.html

Screenshots

Soi4 screens
HarmonyAngel4 screens

Verdict

The call

The clearest difference is in-app purchases: Soi at none against HarmonyAngel's 4. Soi also leads on iOS requirement (10.3 vs 17.0). HarmonyAngel's advantage is update cadence (every 4 weeks vs every 2 months). On price, ads and device support 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

CostPrice · In-app purchases · Ads · Monetization

Both are free to download. HarmonyAngel sells 4 in-app purchases, starting at $0.99 per 7 days. Soi asks for nothing beyond the download.

UpkeepUpdate frequency

Soi ships an update every 2 months, HarmonyAngel every 4 weeks. The most recent releases landed on October 11, 2026 and October 10, 2026 respectively.

Scorecard3 real differences · 7 level
Soi versus HarmonyAngel: the parameters behind the verdict, then further details
ParameterSoiHarmonyAngel
PriceFreeFree
Rating4.0 (2 ratings) — better—
Positive reviews0.0% of reviews—
Number of ratings2 — better—
Update frequencyEvery 2 monthsEvery 4 weeks — better
AdsNoNo
In-app purchasesNo — betterYes
MonetizationFree—
DevicesiPhone, iPad, iPod — betteriPhone, iPad
Requires iOS10.3 — better17.0
Further details — not scored
Size28 MB7 MB
Age rating4+4+
DeveloperAero DekoBetter World Studio

In-app purchases

None

Soi

No in-app purchases

4 purchases

HarmonyAngel

Subscriptions3
  • Weekly Subscription3 Days trial$0.997 Days
  • Monthly Subscription7 Days trial$1.991 Month
  • Yearly Subscription14 Days trial$9.991 Year
One-time1
  • Life-time Purchase$19.99

Questions

Is Soi free?
Soi is free to download, with no in-app purchases.
Is HarmonyAngel free?
HarmonyAngel is free to download, with in-app purchases available.
Do Soi or HarmonyAngel have ads?
Neither Soi nor HarmonyAngel shows ads.
Which is updated more often, Soi or HarmonyAngel?
Soi ships an update every 2 months, and HarmonyAngel every 4 weeks. Most recently, Soi was updated on October 11, 2026 and HarmonyAngel on October 10, 2026.

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