Comparison

CASA Space Frame 3D vs PDF Expert

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

Head to head
About

CASA Space Frame 3D

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
Read full description

Structural / Civil Engineering App for static & dynamic elastic analysis of general 3D space-frames. With CASA SF-3D an engineer can create 3D structural models of space-frames and obtain both the numerical results and graphical representation of the deflections, forces, natural frequencies, and mode shapes. There is an emphasis on quick and precise modelling with graphical interaction. Results are graphically interactive with a sliding readout of numerical results at any point along a member. More information about this App can be found in its integrated help and on our website. The App also contains "Replay Demonstrations" which describe and enact its use. === This App includes the following features: * Linear static analysis. * P-Delta non-linear static analysis. * Natural mode dynamic analysis. * Footfall dynamic analysis. * Sway-cases. * Geometry groups: - Include or exclude geometry from the analysis. - Groups can be combined into supergroups. * Multi-copying for rapid generation of regular geometry. * Rotation and reflection of geometry. * Solid rendering of geometry: - Member cross-sections drawn to scale. - Colour-coded by groups. * Viewpoint memories: - Store and recall for quick navigation. * Members can be oriented to a third node. * Gravity (self-weight) loading. * Factored load-case combinations. * Rubber-band box for large-area selection. === General Technical Features === * Automatic analysis. * Integrated extensive section library: - British, European, American, Canadian, Australian, South African, Japanese, Russian. - See our website for the range of shapes. * Integrated section generator for common shapes: - Open: I/H, channel, zed, angle, tee. - Hollow: Oval, Rectangular. - Solid: Oval, Rectangular. - Calculates: Area, Inertia, Torsional constant, Elastic moduli, mass. * Integrated material library: - Steel, Aluminium, Concrete, Timber, Glass. - User materials can be added. * Member ends can be rigid or pinned. * Loads applied as point, couple, trapezoid. * Multiple load-cases. * Statics results include: - Reactions, deflections, bending moments, shear forces, bending stress. - Points of interest. - Results given all along members. * Dynamic analysis considers self weight plus additional mass-cases. * Dynamic results include:   - Resonant frequencies   - Undamped oscillation mode shapes * Footfall results include: - Response factors. - Critical frequencies. - Both impulse and resonant responses. === General User Interface Features === * Universal App - for iPhone, iPod touch, and iPad. * Metric & imperial units. * Four simple interactive screens: - Geometry, Loading, Results: for interacting with the model. - Utilities: Supplementary functions (see below). * Easy modelling: - Tap to select; tap to edit. - Move and copy geometry. - Slide nodes along members. - Change member spans. - Split members. - Replicate loading across members. * Graphical drag-and-tap controls: - Rotate, pan, zoom the view with simple gestures. - Drag nodes for positions. - Drag loads for positions and magnitudes. - Drag marker along member to read off results values. - Tap on Points of Interest for important results.  - Select nodes to measure distances, angles, and areas between them. * Numeric entry available: - Double-tap on a datum to enter its numerical value. - Includes a convenient built-in calculator. * Straightforward section library: - Pick from country, shape, and size. - View diagram and properties. - For custom shapes, double-tap on dimensions to edit. - Axes can be rotated by 90 degrees. * Report generation: - Configurable content. - Graphical layout. - On-screen preview. - Export PDF by e-mail. - AirPrint. - CSV export of numerical data. * Supplementary functions: - Document titles. - Choice of unit system (UK/EU Metric, US Imperial). - On-line help. - Load, save, and export models.

About

PDF Expert

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
Read full description

PDF Expert is a fast and easy PDF app to read, annotate, fill and sign PDF forms, convert files to PDF, and merge, split or compress documents – all in one intuitive app for iPhone, iPad, Mac & Vision Pro. Read PDF files with comfort, highlight and mark up text, fill out forms, sign contracts, create and convert PDFs, and summarize long documents in seconds with AI-powered tools. Unlock unlimited possibilities with PDF Expert Premium and work across all your Apple devices. "PDF Expert is one of my must-have iPad apps and a desktop-class PDF reader." – MacStories "The best app for managing, editing, and reading PDFs on your iPad." – The Sweet Setup ▶ WITH PDF EXPERT, YOU CAN: READ PDFs - PDF reader with Day, Night, and Sepia modes for comfortable reading anytime - Scroll PDFs vertically or horizontally and search text in any document - Open and view PDF files from email, web, Files, or any app via the Share menu - Read PDFs out loud with Text to Speech ANNOTATE AND MARK UP PDFs - Highlight, underline, and strike through text in your PDFs - Mark up documents with pen, shapes, text, notes, and comments - Add stamps such as Approved or Confidential - Record your voice and add audio notes to PDFs FILL AND SIGN PDF FORMS - Fill out PDF forms with text fields, checkboxes, and radio buttons - Sign PDF documents in seconds – draw your signature or add it from an image - Save your signature to sign contracts, agreements, invoices, and applications faster - Fill, sign, and send forms right from your iPhone – no printing or scanning needed - Supports all major form formats, including AcroForms and static XFA forms ***PREMIUM FEATURES*** EDIT PDFs - Edit text directly in a PDF – just as you would in a Word document - Add, replace, and resize images in your PDFs - Add links to other pages or websites - Add outlines to navigate large PDFs CREATE AND CONVERT PDFs - Create PDFs from Word files, images, and other documents - Convert Word to PDF, JPG to PDF, and PNG to PDF in seconds - Convert PDF to Word, Excel, PowerPoint, JPG, PNG, and TXT MERGE, SPLIT AND ORGANIZE PDFs - Merge and combine multiple PDF files into one - Split PDFs and extract pages into a new file - Add, delete, rotate, and reorder pages with thumbnail preview COMPRESS PDFs - Compress PDFs to reduce file size for email and sharing - Shrink large PDF files to save space on your device SUMMARIZE PDFs WITH AI – PDF COPILOT - List Main Points – get key takeaways from any PDF - Summarize – get concise summaries of entire PDFs or annotations - Ask Anything – find details with AI answers and references - Explain – get instant explanations of words or phrases PROTECT YOUR FILES - Password-protect PDF Expert - Redact – permanently black out sensitive information WORK WITH SCANNED DOCUMENTS - Open scanned PDFs to fill out, sign, annotate, and share CONSTRUCTION TOOLS - Scale and measure drawings with the Measure tab - Polygon, polyline, and redline tools MORE FEATURES - Customizable toolbar - Presentation Mode - Print and share PDFs via email or cloud ONE ACCOUNT FOR ALL YOUR APPLE DEVICES One Premium subscription covers PDF Expert on iPhone, iPad, and Mac – no need to buy versions separately. Read more about our terms and conditions here: https://pdfexpert.com/privacy https://pdfexpert.com/terms Don’t hesitate to reach out to us at http://readdle.com/contact

Screenshots

CASA Space Frame 3D4 screens
PDF Expert4 screens

Verdict

The call

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.

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

CostPrice · In-app purchases · Ads · Monetization

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.

ReceptionRating · Positive reviews · Number of ratings

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.

UpkeepUpdate frequency

CASA Space Frame 3D ships an update every 3 months, PDF Expert fortnightly. The most recent releases landed on October 5, 2026 and October 18, 2026 respectively.

Scorecard9 real differences · 2 level
CASA Space Frame 3D versus PDF Expert: the parameters behind the verdict, then further details
ParameterCASA Space Frame 3DPDF Expert
Price$299.99Free — better
Rating4.0 (1 ratings)4.7 (216K ratings) — better
Positive reviews100.0% of reviews — better45.5% of reviews
Number of ratings1216K — better
Update frequencyEvery 3 monthsFortnightly — better
AdsNoNo
In-app purchasesNo — betterYes
MonetizationPaidFree with in-app purchases — better
Best chart rank—#86 — better
DevicesiPhone, iPad, iPod — betteriPhone, iPad
Requires iOS14.1 — better16.0
Further details — not scored
Size6 MB295 MB
Age rating4+4+
DeveloperIntesym Ltd.Readdle Technologies Limited

Customer experience

CASA Space Frame 3D

All ratings1 ratings
Positive100.0%
Neutral0.0%
Negative0.0%
Written reviews3 reviews
Positive100.0%
Neutral0.0%
Negative0.0%

PDF Expert

All ratings216,128 ratings
Positive92.4%
Neutral2.3%
Negative5.3%
Written reviews1,166 reviews
Positive45.5%
Neutral7.5%
Negative47.0%

Bugs and requests

CASA Space Frame 3D

Not enough reviews yet to summarise bugs or requests.

PDF Expert

Reported bugs

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

Requested features

5 requests
  • 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

In-app purchases

None

CASA Space Frame 3D

No in-app purchases

10 purchases

PDF Expert

Subscriptions9
  • PDF Expert Premium Trial7 Days trial$9.991 Month
  • PDF Expert Premium No Trial$9.991 Month
  • PDF Expert for Education7 Days trial$39.991 Year
Show 6 more
  • PDF Expert Premium7 Days trial3 variants$49.991 Year
  • PDF Expert Premium New7 Days trial$49.991 Year
  • PDF Expert Premium Existing7 Days trial$49.991 Year
  • PDF Expert – Premium Editing1 Year trial$49.991 Year
  • PDF Expert Mac & iOS Pro7 Days trial$79.991 Year
  • PDF Expert Mac & iOS7 Days trial$79.991 Year
One-time1
  • PDF Expert Basic$9.99

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 18, 2026.

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