Fast STL Viewer

Fast STL Viewer

Contains adsIn-app purchases

About this app

Professional STL inspection and measurement on Android. Wall thickness analysis, printability checks, point-to-point distance, volume, surface area, cross-sections — tools that used to require a desktop workstation, now in your pocket.

Trusted by engineers, dental technicians, medical device teams, jewellery designers, and quality control inspectors worldwide. Over 1 million downloads.

PRO INSPECTION TOOLS

▸ Wall Thickness Heatmap
Spot thin walls and weak points before they become print failures. Color-coded heatmap (red → yellow → green) maps thickness across your entire model. First mobile STL viewer with wall thickness analysis.

▸ Printability Dashboard
Four automated mesh checks: open edges, flipped normals, non-manifold geometry, degenerate triangles. Interactive 3D overlay highlights each issue directly on your model. Catch defects before they waste material and machine time.

▸ Normal Visualization
Per-face normal vectors with adjustable length, color, and thickness. Verify surface orientation at a glance — essential for diagnosing reversed faces and print artifacts.

▸ Cross-Section Slicing
Adjustable X, Y, Z cutting planes to inspect internal geometry. See what's inside without splitting the file.

MEASUREMENT TOOLS
- Point-to-point distance — tap two points, get the dimension
- Volume and surface area with unit selector (mm, cm, in)
- Bounding box dimensions (X, Y, Z)
- Properties panel: triangle count, dimensions, full geometry stats

VISUALIZATION
- 5 rendering modes: shaded, wireframe, combined, point cloud, normals
- 6 standard views: top, bottom, left, right, front, back
- Orthographic projection for accurate dimensional inspection
- Custom mesh, scene, wireframe, and point cloud colors
- Adjustable lighting — matte to glossy material appearance
- Automatic detection of unconnected components within a single file — instantly color-coded for assembly review
- Open boundary detection — identify non-watertight geometry before printing

WORKFLOW
- Load multiple STL files for side-by-side comparison
- Open from Gmail, Google Drive, WhatsApp, or any file manager
- Share STL files directly from any app
- Select and open multiple files at once via the in-app file picker
- Save and export

BUILT FOR PERFORMANCE
OpenGL ES 3.2 and native C++ with hardware-accelerated mesh analysis. Handles files with millions of triangles. Binary and ASCII STL.

USED BY PROFESSIONALS IN
◆ Engineering & QC — Verify wall thickness on brackets, housings, and structural components. Inspect cross-sections. Measure dimensions before manufacturing. On-device inspection for incoming parts.
◆ 3D Printing — Run printability checks before every print. Open edges, flipped normals, thin walls — catch them before they cause failures.
◆ Dental — Inspect crowns, bridges, and aligners. Measure dimensions, verify wall thickness on thin anatomical geometry.
◆ Medical Devices — Review implant and prosthetic STL files. Cross-section through anatomy, verify specs.
◆ Jewellery — Wall thickness on filigree and prong settings. Mesh integrity before casting.

Try any Pro feature free — watch a short video to unlock for 1 hour. Upgrade to Pro to keep them all.

Ratings and reviews

The app is okay, it does the job and I can open from Google Drive. Can't say there is a lot of competition for stl viewer apps. I do wish it didn't use the annoying full screen, timed ads. those are the absolute worst and I usually instantly uninstall any app that uses those ads, but again, there aren't really any other options for stl viewer apps. At the very least please add a paid option that is a one time fee just to remove ads, in sorry but I am not going to pay a subscription for this.

the recent ads, even worse now, uninstalling and finding a better one. edit for developer: I doubt many people use the file > open to access a stl file. If we download a batch of stls we close then the app is auto selected via the phone when we open stl #2, that's one ad per file opened. furthermore, I had used this app for years while making ornaments (4+ years) it was NEVER this bad and it had always been free. something changed and it's going to cause the app score to take a dive.

This used to be a really handy app with ads at the top which were fairly well behaved. unfortunately now they are those full-screen ads for games that go on and on which royally sucks. I associated this app with stl files so each time I click on an stl file in my file manager to view, this app pukes up one of those awful, soul-crushing, time wasting ads. There is no "pay to remove ads" option or a paid pro version so this is now getting uninstalled. What a terrible waste of a once fine app.

What’s new

Improved lighting, Wireframe and Points modes, plus bug fixes for opening STL files from external apps and file managers.