Comparison

GD&T HD vs Cadaclysm

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

Head to head
About

GD&T HD

This app serves as a multimedia reference for understanding geometric dimensioning and tolerancing (GD&T) according to ISO 1101. It provides definitions, examples, and animations to help engineers and employees interpret and inspect GD&T concepts like form, position, and orientation tolerances.

Highlights
  • ISO 1101 GD&T definitions
  • Multimedia reference book
  • Practical interpretation examples
  • Form and position tolerance handling
  • 25 animations
  • Basic information
Read full description

Learn, interpret and inspect GD&T according to ISO 1101. This app describes a large range of definitions of geometric dimensioning and tolerancing and supports engineers and employees as a multimedia reference book. As part of operative education, this app shows relationships and makes it easier to understand the right handling of form and position tolerances in practice. This app explains the most important definitions of GD&T and its interpretation by examples (straightness, roundness, flatness, cylindricity, profile of a line, parallelism, squareness, angularity, position, concentricity, symmetry, circular runout, …) -25 animations -Basic information -Form tolerance -Profile tolerance -Position tolerance -Orientation tolerance -Runout tolerance

About

Cadaclysm

Features
Read full description

Cadaclysm opens real CAD files on your iPhone and iPad: the exact B-rep geometry inside a STEP, IFC, 3DM, IGES, SAT or BREP file, read and meshed on the device itself. Nothing is uploaded, no account is needed, and it works with no network at all. FORMATS • STEP (.step, .stp) — AP203, AP214, AP242 and the other schemas ship inside the app • IFC (.ifc) — IFC2x3, IFC4 and IFC4x3, with every element's property sets • 3DM (.3dm) • IGES (.iges, .igs) • ACIS (.sat) • BREP (.brep, .brp), as written by OCCT • OpenSCAD (.scad) — evaluated on the device OPEN A FILE FROM ANYWHERE Pick a file from the Files app, including iCloud Drive and other cloud storage, or send it to Cadaclysm from the Share sheet of Mail, Messages, WhatsApp or any other app. A model someone sends you is two taps away. BUILT FOR BIG MODELS The reader is written in Rust and runs natively on your device. Assemblies with thousands of parts open with a live progress bar, and a memory budget keeps the largest ones on screen at reduced detail instead of running out of memory. Level of detail follows the camera: fine where you look, coarse where you don't. A TOUCH CAMERA THAT STAYS OUT OF THE WAY One finger orbits. Two fingers pan and pinch at the same time. Double-tap frames the whole model. Tap an axis on the triad for a front, top or side view in parallel projection, tap it again for the far side. BROWSE THE PARTS A translucent parts tree slides over the model without hiding it. Expand assemblies, tap a part to select it, frame it, isolate it, or hide whole subtrees with one tap. Search with plain names or with filter expressions (name, type, layer, properties). Every part opens a details panel with its properties — for IFC, the full property sets from the file. SEE THE GEOMETRY, NOT JUST THE SHADING Toggle four layers independently: shapes, edges, curves and isocurves. Give each wire kind its own colour or let it follow the part's colour. Pick a background, turn the grid on or off, and switch a Y-up model (a game-engine export) to show the right way up. TUNE IT FOR YOUR DEVICE Render scale, anti-aliasing, half-precision geometry and detail-while-moving are all adjustable, so an older iPhone stays smooth and an iPad Pro shows everything. SHARE A PICTURE Export the current view as a high-resolution PNG with a transparent background, rendered well beyond the screen's size with crisp edges, and share it from the Share sheet to any app. KNOW WHAT YOU OPENED The document panel lists the file, its reader, what it contains, what the scene was built from, the file's own properties and the reader's diagnostics — the same words the desktop tools use, so a problem can be reported precisely. PRIVATE BY DESIGN Cadaclysm never sends your files anywhere. There are no accounts, no ads and no analytics, and it collects no data. The models on your device stay on your device. Cadaclysm is built on the Cadaclysm geometry library, the same readers, mesher and B-rep kernel that power its desktop, web and game-engine integrations. Questions, models that will not open, ideas: join the Discord from the About screen. Screenshots show a quadcopter assembly built with the Cadaclysm kernel, sample models from NIST's MBE PMI test cases, and the OpenSCAD examples (CC0). ACIS is a trademark of Spatial Corp. and Open CASCADE (OCCT) of Open Cascade SAS; other product names belong to their owners. Cadaclysm is not affiliated with or endorsed by any of them: the names only say which files it reads.

Screenshots

Cadaclysm4 screens

Verdict

The call

The clearest difference is update cadence: Cadaclysm at every 4 days against GD&T HD's every 11 months. GD&T HD's advantage is iOS requirement (15.0 vs 17.0). On price, ads, in-app purchases 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

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

UpkeepUpdate frequency

GD&T HD ships an update every 11 months, Cadaclysm every 4 days. The most recent releases landed on November 1, 2026 and October 29, 2026 respectively.

Scorecard2 real differences · 8 level
GD&T HD versus Cadaclysm: the parameters behind the verdict, then further details
ParameterGD&T HDCadaclysm
PriceFreeFree
Rating2.0 (1 ratings) — better—
Positive reviews0.0% of reviews—
Number of ratings1 — better—
Update frequencyEvery 11 monthsEvery 4 days — better
AdsNoNo
In-app purchasesNoNo
MonetizationFree—
DevicesiPadiPhone, iPad — better
Requires iOS15.0 — better17.0
Further details — not scored
Size56 MB12 MB
Age rating4+4+
DeveloperCarl Zeiss AGBlitter

In-app purchases

None

GD&T HD

No in-app purchases

None

Cadaclysm

No in-app purchases

Questions

Is GD&T HD free?
GD&T HD is free to download, with no in-app purchases.
Is Cadaclysm free?
Cadaclysm is free to download, with no in-app purchases.
Do GD&T HD or Cadaclysm have ads?
Neither GD&T HD nor Cadaclysm shows ads.
Which is updated more often, GD&T HD or Cadaclysm?
GD&T HD ships an update every 11 months, and Cadaclysm every 4 days. Most recently, GD&T HD was updated on November 1, 2026 and Cadaclysm on October 29, 2026.

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