Dioptra: GLB 3D Model Viewer
Productivity
Free · In‑App Purchases · Designed for iPad. Not verified for macOS.
A 3D model viewer for iPhone and iPad that takes measurement seriously.
Open a file, turn it over, and tap two points on the surface to get a real distance.
FORMATS
• glTF — .glb and .gltf
• USD — .usdz, .usdc, .usda and .usd
• STL — 3D prints and CAD exports, read in millimetres and turned upright
• PLY — scans and photogrammetry, with per-vertex colour
• VRM
• Interactive pages — an .html export keeps its own controls and runs as it was built
MEASURE
• Tap two points for a true distance
• Take as many measurements as you need; they stay listed with the model
• Switch between metric and imperial whenever you like
• Set what one file unit means: metres, centimetres, millimetres, inches or feet
INSPECT
• Orbit, pan and zoom, or leave it turning on its own
• Wireframe, to see how a mesh is built
• Studio, light and dark backgrounds
• Play embedded animations, one clip at a time
• Model info: width, height and depth, plus triangles, vertices, meshes, materials, textures, nodes and animations
• Share a snapshot of the view
ORGANISE
• Folders, which appear in the Files app exactly as they do here
• Search, sort by name, type or date, and switch between a list and a grid
• Rename, drag a model onto a folder to file it, or delete it
• Bring models in with the picker, from another app's share sheet, or by dropping them into the Dioptra folder in Files
SAMPLES
Six models come with the app, one for each kind of file it opens, all built to real-world scale: the ancient sighting instrument the app is named for, a Roman surveyor's groma, a sundial's gnomon, a tripod foot in millimetres, a surveyed patch of terrain, and an interactive plan of sight lines.
PRIVATE BY DEFAULT
No account, no sign-in, no cloud, no tracking and no ads. Your models stay on your device and everything works offline.
Ratings & Reviews
- This app hasn’t received enough ratings or reviews to display an overview.
Bug fixes and improvements
The developer, Zachary Griffin, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Collected
The developer does not collect any data from this app.
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- Zachary Griffin
- Size
- 5.3 MB
- Category
- Productivity
- Compatibility
Requires iOS 17.0 or later.
- iPhone
Requires iOS 17.0 or later. - iPad
Requires iPadOS 17.0 or later. - Mac
Requires macOS 14.0 or later and a Mac with Apple M1 chip or later. - Apple Vision
Requires visionOS 1.0 or later.
- iPhone
- Languages
- English
- Age Rating
4+
- 4+
- In-App Purchases
Yes
- Generous Tip $4.99
- Tip $1.99
- Small Tip $0.99
- Copyright
- © 2026 Zachary Griffin