# Petal Layout Pro vs STEP Viewer

The clearest difference is price: STEP Viewer at Free against Petal Layout Pro's $3.99. STEP Viewer also leads on update cadence (every 5 days vs every 41 months) and iOS requirement (13.0 vs 16.1). On ads, in-app purchases and device support there is nothing between them.

STEP Viewer is free to download; Petal Layout Pro costs $3.99 up front. Neither carries in-app purchases, so what you see is what you pay.

Petal Layout Pro ships an update every 41 months, STEP Viewer every 5 days. The most recent releases landed on September 15, 2026 and September 17, 2026 respectively.

## The numbers

| Metric | Petal Layout Pro | STEP Viewer |
| --- | --- | --- |
| Price | $3.99 | **Free** |
| Positive reviews | 0.0% of reviews | — |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 41 months | **Every 5 days** |
| Monetization | Paid | — |
| Size | 1 MB | 61 MB |
| Requires iOS | 16.1 | **13.0** |
| Devices | iPhone, iPad | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [Imran Pinjara](https://appshunter.io/developer/1484488781) | [Smart Cube Labs Co., Ltd.](https://appshunter.io/developer/1456342688) |

## What reviewers say

### Petal Layout Pro

[App page](https://appshunter.io/ios/app/petal-layout-pro/id1486823832)

This app assists in the fabrication of spherical and hemispherical heads by calculating precise petal layouts. It supports various part divisions for accurate flat pattern development, ideal for pressure vessel and storage tank construction.

**Highlights:** Sphere petal layout calculation, Hemispherical head petal layout calculation, Multiple part divisions (12, 24, 48), Unit setting for mm/inches, Flat pattern development, Supports pressure vessel fabrication

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases:** none


### STEP Viewer

[App page](https://appshunter.io/ios/app/step-viewer/id6756539299)

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases:** none


## Frequently asked questions

### Is Petal Layout Pro free?

Petal Layout Pro costs $3.99, with no in-app purchases.

### Is STEP Viewer free?

STEP Viewer is free to download, with no in-app purchases.

### Do Petal Layout Pro or STEP Viewer have ads?

Neither Petal Layout Pro nor STEP Viewer shows ads.

### Which is updated more often, Petal Layout Pro or STEP Viewer?

Petal Layout Pro ships an update every 41 months, and STEP Viewer every 5 days. Most recently, Petal Layout Pro was updated on September 15, 2026 and STEP Viewer on September 17, 2026.

---

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