Comparison

Opus vs Fluid Sonata

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

Head to head
About

Opus

Features
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Opus is a classical listening companion for people who want to understand the music as it unfolds. Start from the player you already use. Opus works with Apple Music, Apple Music Classical, Spotify, and shared track links from other music apps, so a piece can become clearer whether you are listening live or returning to a recording you found elsewhere. As the music plays, Opus helps you move from the passage in front of you to the larger work around it: the composer, the structure, the form, and the world that shaped the music. Opus creates AI-assisted listening introductions that stay close to the music instead of interrupting it, so a symphony, sonata, concerto, or opera becomes easier to follow while you are still inside the experience. Choose the depth that suits the way you listen. Listener is free and offers a welcoming way in, with a clear sense of mood, character, and dramatic shape. Enthusiast opens a broader view of structure and musical context, helping you follow themes, contrasts, and the arc of the work. Connoisseur goes further into form, style, and interpretive detail for listeners who want a deeper reading of what they hear. Whether you are meeting a piece for the first time or returning to a familiar recording, Opus helps you listen with sharper ears and a stronger sense of the work as a whole. Terms of Service: https://opus.cyberic.app/en/terms-of-service Privacy Policy: https://opus.cyberic.app/en/privacy-policy

About

Fluid Sonata

Features
Read full description

A fluid simulation and a classical performance, both generated live on your phone, wired to the same clock. There are no audio files in this app and no video. A piano is synthesized from scratch every time you press play β€” a fundamental plus four slightly sharp partials, a hammer thud on the attack, a small hall around it β€” and every note it plays is thrown into a real Navier-Stokes fluid solver running on the GPU. The left hand punches jets up from the floor. The right hand lands at an x position taken from its own pitch, so the melody plays the screen like a keyboard. Behind it all, a ten-body Newtonian integrator runs the actual solar system, on a real date. TEN SCORES, FOURTEEN READINGS Seven pieces from the public-domain canon β€” Bach's Prelude in C, Mozart's Rondo alla Turca, Beethoven's FΓΌr Elise, Ode to Joy and the Moonlight Presto, Tchaikovsky's Trepak, Grieg's In the Hall of the Mountain King β€” plus three originals written for this app. Every score plays fourteen ways: piano recital, cathedral organ, strings, music box, jazz trio, electric guitar, synth, 8-bit, 16-bit, drums, deep bass, disco, techno and an EDM remix. Every instrument is synthesized from scratch β€” there is not one audio file in this app. LISTEN TO THE ROOM Turn on Listen Mode and the fluid dances to whatever is playing near you β€” another app, a speaker, someone at a piano. The microphone reaches the analyser and nothing else: nothing is recorded, stored or sent, and turning it off releases the microphone. TWO WAYS TO DRIVE IT ORBITAL Click puts everything on a circular touch surface β€” a thumb travelling around the ring moves the selection, with real detents you can feel and acceleration when you spin. Fluid Classic is a conventional dock and player. Pick either in Settings; everything is reachable from both. STATIONS Three stations of music that is genuinely free to play, streamed from the Internet Archive: classical sides digitised by the Great 78 Project, and recordings Musopen commissioned and released for anyone to use. Every track earns its place by a rule that is checked when the list is built, not assumed. PLAY YOUR OWN MUSIC Hand it any song on your device and the fluid dances to that instead. A live spectrum analysis drives the same choreography the written scores use. The file is decoded on your phone and never uploaded β€” the app has nowhere to send it. RECORD THE STAGE Capture the fluid, the orrery and the music together, then save the clip to Files or Photos or send it straight on. PRIVATE BY ARCHITECTURE, NOT BY POLICY No account. No analytics. No third-party SDKs. No tracking. Nothing you do here is collected. The app asks for one permission β€” the microphone, and only if you turn on Listen Mode. The whole engine ships inside the app, and the scores, your own songs and the simulation all run with the network switched off. Three things do reach out, and the app tells you which: a once-a-day check with Apple for a newer version, carrying nothing but the app's own identifier; StoreKit, to price the Full Concert; and β€” only when you choose a Station β€” the recording you asked for. FREE FOREVER, AND A ONE-TIME UNLOCK Moonlight Β· Presto, FΓΌr Elise, the Classical reading and the EDM remix are free forever, with no time limit and no ads. The Full Concert unlocks the remaining scores and readings with a single purchase β€” no subscription, and it is shared with your family. Also on iPad. Made by djEnterprises.

Screenshots

Opus4 screens
Fluid Sonata4 screens

Verdict

The call

Opus and Fluid Sonata are too close to call on the numbers: across 5 compared parameters β€” price, ads, in-app purchases and device support among them β€” neither pulls far enough ahead to decide it. What separates them is feature set and interface, not measurable difference.

Scored on Price Β· Rating Β· Positive reviews Β· Number of ratings Β· Update frequency Β· Ads Β· In-app purchases Β· Monetization Β· Best chart rank Β· Devices Β· Requires iOS

CostPrice Β· In-app purchases Β· Ads Β· Monetization

Both are free to download. Opus sells 2 in-app purchases, starting at $5.99 per month and Fluid Sonata sells 1 one-off in-app purchase. Whichever you choose, the download price is not the number that matters.

ScorecardNo meaningful differences
Opus versus Fluid Sonata: the parameters behind the verdict, then further details
ParameterOpusFluid Sonata
PriceFreeFree
Update frequencyWeeklyβ€”
AdsNoNo
In-app purchasesYesYes
DevicesiPhone, iPadiPhone, iPad
Requires iOS18.017.0 β€” better
Further details β€” not scored
Size130 MB5 MB
Age rating4+4+
DeveloperCyberic LimitedDaniel Ehrlich

In-app purchases

2 purchases

Opus

Subscriptions2
  • Monthly$5.991 Month
  • Annual$49.991 Year
1 purchases

Fluid Sonata

One-time1
  • The Full Concert$4.99

Questions

Is Opus free?
Opus is free to download, with in-app purchases available.
Is Fluid Sonata free?
Fluid Sonata is free to download, with in-app purchases available.
Do Opus or Fluid Sonata have ads?
Neither Opus nor Fluid Sonata shows ads.

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