# TopOpt vs Cat Liquid Slide Puzzle

The clearest difference is in-app purchases: TopOpt at none against Cat Liquid Slide Puzzle's 1. TopOpt also leads on ads (none vs shown). Cat Liquid Slide Puzzle's advantage is update cadence (every 3 weeks vs every 4 months). On price, device support and iOS requirement there is nothing between them.

Both are free to download. Cat Liquid Slide Puzzle sells 1 one-off in-app purchase. TopOpt asks for nothing beyond the download.

TopOpt ships an update every 4 months, Cat Liquid Slide Puzzle every 3 weeks. The most recent releases landed on November 1, 2026 and October 30, 2026 respectively.

## The numbers

| Metric | TopOpt | Cat Liquid Slide Puzzle |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[5.0 (2 ratings)](https://appshunter.io/ios/app/topopt/id507454646/reviews)** | — |
| Number of ratings | **2** | — |
| Positive reviews | 66.7% of reviews | — |
| In-app purchases | **No** | Yes |
| Ads | **No** | Yes |
| Update frequency | Every 4 months | **Every 3 weeks** |
| Monetization | Free | — |
| Size | 51 MB | 143 MB |
| Requires iOS | 15.0 | 15.0 |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 4+ |
| Developer | [DTU Mechanical Engineering](https://appshunter.io/developer/507453160) | [Yusuke Okada](https://appshunter.io/developer/1793725878) |

## What reviewers say

### TopOpt

[App page](https://appshunter.io/ios/app/topopt/id507454646)

Explore structural engineering concepts with an interactive topology optimization tool. Design and visualize optimized structures in real-time by placing loads and supports. Supports advanced features like volume and stress constraints for detailed analysis.

**Highlights:** Real-time structure updates, Minimum compliance optimization, Compliant mechanisms design, Local volume and stress constraints, Robust formulation for design insensitivity, STL export for 3D printing, Interactive load and support placement

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

**In-app purchases:** none


### Cat Liquid Slide Puzzle

[App page](https://appshunter.io/ios/app/cat-liquid-slide-puzzle/id6751434642)

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

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Remove Ads | $0.49 | one-time |


## Frequently asked questions

### Is TopOpt free?

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

### Is Cat Liquid Slide Puzzle free?

Cat Liquid Slide Puzzle is free to download, with in-app purchases available.

### Do TopOpt or Cat Liquid Slide Puzzle have ads?

Cat Liquid Slide Puzzle shows ads; TopOpt does not.

### Which is updated more often, TopOpt or Cat Liquid Slide Puzzle?

TopOpt ships an update every 4 months, and Cat Liquid Slide Puzzle every 3 weeks. Most recently, TopOpt was updated on November 1, 2026 and Cat Liquid Slide Puzzle on October 30, 2026.

---

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