# CASA Space Frame 3D vs PDF Expert

The clearest difference is review sentiment: CASA Space Frame 3D at 100% against PDF Expert's 45%. CASA Space Frame 3D also leads on in-app purchases (none vs 12) and iOS requirement (14.1 vs 16.0). PDF Expert's advantage is price (Free vs $299.99) and rating (4.7 vs 4.0). On ads and device support there is nothing between them.

PDF Expert is free to download; CASA Space Frame 3D costs $299.99 up front. PDF Expert sells 10 in-app purchases, starting at $9.99 per month. CASA Space Frame 3D asks for nothing beyond the download.

PDF Expert holds the better App Store score, 4.7 against 4.0. That said, the two scores are not equally well evidenced: PDF Expert has 216K ratings behind it against 1, so its average is the more settled of the two. Written reviews complicate that: 100% of CASA Space Frame 3D's written reviews are positive against 45% of PDF Expert's, so the app with the better star average is not the one people write more warmly about.

CASA Space Frame 3D ships an update every 3 months, PDF Expert fortnightly. The most recent releases landed on October 5, 2026 and October 19, 2026 respectively.

## The numbers

| Metric | CASA Space Frame 3D | PDF Expert |
| --- | --- | --- |
| Price | $299.99 | **Free** |
| Rating | [4.0 (1 ratings)](https://appshunter.io/ios/app/casa-space-frame-3d/id371089612/reviews) | **[4.7 (216K ratings)](https://appshunter.io/ios/app/pdf-expert-editor-and-reader/id743974925/reviews)** |
| Number of ratings | 1 | **216K** |
| Positive reviews | **100.0% of reviews** | 45.4% of reviews |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Every 3 months | **Fortnightly** |
| Monetization | Paid | **Free with in-app purchases** |
| Best chart rank | — | **#90** |
| Size | 6 MB | 295 MB |
| Requires iOS | **14.1** | 16.0 |
| Devices | **iPhone, iPad, iPod** | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [Intesym Ltd.](https://appshunter.io/developer/361434891) | [Readdle Technologies Limited](https://appshunter.io/developer/285035419) |

## What reviewers say

### CASA Space Frame 3D

[App page](https://appshunter.io/ios/app/casa-space-frame-3d/id371089612)

This app enables structural engineers to perform static and dynamic elastic analysis of 3D space-frames. It offers quick and precise modeling with graphical interaction, providing numerical and graphical results for deflections, forces, and mode shapes.

**Highlights:** Linear static analysis, Non-linear static analysis (P-Delta), Dynamic analysis (natural modes, footfall), Extensive section and material libraries, Graphical interactive results, Metric & imperial units

**In-app purchases:** none


### PDF Expert

[App page](https://appshunter.io/ios/app/pdf-expert-editor-and-reader/id743974925)

**Currently charting:** #90 Top Grossing · Productivity (US App Store)

This app allows you to edit, annotate, fill out forms, and convert PDF documents. It offers AI-powered summarization and analysis, along with tools to merge, sign, and protect your files. Work seamlessly across Apple devices with a user-friendly interface.

**Highlights:** Edit PDF text and images, Annotate and highlight PDFs, Fill out PDF forms, Convert files to and from PDF, AI-powered summarization and analysis, Merge and combine PDF files, Sign documents with e-signatures

**Features:** Vision Pro support

**In-app purchases (10)**

| Purchase | Price | Billing |
| --- | --- | --- |
| PDF Expert Premium Trial | $9.99 | per month |
| PDF Expert Premium No Trial | $9.99 | per month |
| PDF Expert for Education | $39.99 | per year |
| PDF Expert Premium | $49.99 | per year |
| PDF Expert Premium New | $49.99 | per year |
| PDF Expert Premium Existing | $49.99 | per year |
| PDF Expert – Premium Editing | $49.99 | per year |
| PDF Expert Mac & iOS Pro | $79.99 | per year |
| PDF Expert Mac & iOS | $79.99 | per year |
| PDF Expert Basic | $9.99 | one-time |

**What reviewers like**

- 🚀 Fast and responsive
- 👍 Intuitive and user-friendly interface
- 💡 Powerful annotation and editing tools
- 🔒 Seamless cloud integration
- 📚 Excellent for reading and organizing PDFs

**What reviewers complain about**

- 🐛 Frequent crashes and stability issues
- 🔒 Subscription model for advanced features
- 🔒 Inconsistent pricing and feature changes
- 🔍 Cluttered and confusing UI in latest update
- 🔍 Reduced customization options for annotations

**Reported bugs**

- Corrupted PDFs after editing
- Sync issues with cloud storage providers
- Unexpected loss of annotations and edits
- Unreliable performance on older iPad models

**Requested features**

- Improved palm rejection for Apple Pencil
- Customizable toolbar and annotation presets
- Better integration with other productivity apps
- More flexible file management and organization
- Ability to create fillable PDF forms


## Frequently asked questions

### Is CASA Space Frame 3D free?

CASA Space Frame 3D costs $299.99, with no in-app purchases.

### Is PDF Expert free?

PDF Expert is free to download, with in-app purchases available.

### Which has better reviews, CASA Space Frame 3D or PDF Expert?

PDF Expert is rated higher. CASA Space Frame 3D averages 4.0 out of 5 from 1 ratings, while PDF Expert averages 4.7 from 216K ratings.

### Do CASA Space Frame 3D or PDF Expert have ads?

Neither CASA Space Frame 3D nor PDF Expert shows ads.

### Which is updated more often, CASA Space Frame 3D or PDF Expert?

CASA Space Frame 3D ships an update every 3 months, and PDF Expert fortnightly. Most recently, CASA Space Frame 3D was updated on October 5, 2026 and PDF Expert on October 19, 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.*