# Polythemus AU vs Surface Builder

The clearest difference is price: Polythemus AU at $3.99 against Surface Builder's $14.99. Polythemus AU also leads on iOS requirement (11.0 vs 13). Surface Builder's advantage is review sentiment (80% vs 57%) and rating (4.7 vs 4.4). On ratings volume, update cadence, ads and in-app purchases there is nothing between them.

Polythemus AU costs $3.99 and Surface Builder $14.99 up front. Neither carries in-app purchases, so what you see is what you pay.

Surface Builder holds the better App Store score, 4.7 against 4.4. Both are backed by a comparable volume of ratings — 7 and 15 respectively. Written reviews point the same way: 57% of Polythemus AU's written reviews are positive against 80% of Surface Builder's.

Polythemus AU ships an update fortnightly, Surface Builder every 3 weeks. The most recent releases landed on October 15, 2026 and October 12, 2026 respectively.

## The numbers

| Metric | Polythemus AU | Surface Builder |
| --- | --- | --- |
| Price | **$3.99** | $14.99 |
| Rating | [4.4 (7 ratings)](https://appshunter.io/ios/app/polythemus-au/id1439815017/reviews) | **[4.7 (15 ratings)](https://appshunter.io/ios/app/surface-builder/id6449735778/reviews)** |
| Number of ratings | 7 | **15** |
| Positive reviews | 57.1% of reviews | **80.0% of reviews** |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | **Fortnightly** | Every 3 weeks |
| Monetization | Paid | Paid |
| Size | 15 MB | 32 MB |
| Requires iOS | **11.0** | 13 |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 4+ |
| Developer | [anthony saunders](https://appshunter.io/developer/460303742) | [4Pockets.com](https://appshunter.io/developer/370131860) |

## What reviewers say

### Polythemus AU

[App page](https://appshunter.io/ios/app/polythemus-au/id1439815017)

This app transforms MIDI chords into individual monophonic MIDI channels. It allows you to create polyphonic synthesizers from monophonic ones, add rhythmic variations to sequences, and control external hardware synths. It offers individual voice management for number of voices, muting, velocity scaling, and transposition.

**Highlights:** Create polyphonic synths from monophonic ones, Stack synths for variation, Add timbre and rhythm variations, Control external hardware synths, Voice allocation and management, MIDI velocity scaling per voice, Transpose MIDI output per voice

**In-app purchases:** none


### Surface Builder

[App page](https://appshunter.io/ios/app/surface-builder/id6449735778)

Create custom MIDI control surfaces for audio applications. Design interfaces with buttons, knobs, and faders to send and receive MIDI data, control audio clips, and customize appearance. Supports AUv3 plugins and standalone use.

**Highlights:** Customizable MIDI control surfaces, AUv3 plugin and standalone modes, Send/receive MIDI data (notes, controllers, pitch bend), Audio clip playback control, Multi-scene interface design, Drag and drop interface customization

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is Polythemus AU free?

Polythemus AU costs $3.99, with no in-app purchases.

### Is Surface Builder free?

Surface Builder costs $14.99, with no in-app purchases.

### Which has better reviews, Polythemus AU or Surface Builder?

Surface Builder is rated higher. Polythemus AU averages 4.4 out of 5 from 7 ratings, while Surface Builder averages 4.7 from 15 ratings.

### Do Polythemus AU or Surface Builder have ads?

Neither Polythemus AU nor Surface Builder shows ads.

### Which is updated more often, Polythemus AU or Surface Builder?

Polythemus AU ships an update fortnightly, and Surface Builder every 3 weeks. Most recently, Polythemus AU was updated on October 15, 2026 and Surface Builder on October 12, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*