Fast STL Viewer

Contains adsIn-app purchases
3.7
4.17K reviews
1M+
Downloads
Content rating
Everyone
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About this app

Inspect, measure, and analyze STL files on your Android device. Used by engineers, dental technicians, medical professionals, educators, and quality control teams worldwide. Over 1 million downloads.

PROFESSIONAL TOOLS
Volume and surface area measurement with unit selector (mm, cm, in). Slice view with adjustable X, Y, and Z cross-section sliders to inspect internal geometry. Custom color settings for front and back faces. Remove all ads with a Pro subscription.

CORE FEATURES
- Load multiple STL files simultaneously for side-by-side comparison
- 4 rendering modes: shaded, wireframe, combined, and point cloud
- 6 standard views: top, bottom, left, right, front, back
- Automatic part detection — find and color-code separate components
- Boundary detection — identify open edges and mesh issues
- Orthographic projection for precise inspection
- Open STL files from email, Google Drive, Dropbox, or any file manager
- Save and export models

BUILT FOR PERFORMANCE
Powered by OpenGL ES 3.2 and native C++ mesh processing. Handles large STL files with millions of triangles. Supports both binary and ASCII formats.

Whether you are checking a dental crown, inspecting an engineering bracket, reviewing a medical implant, or teaching a CAD course — Fast STL Viewer gives you professional inspection tools in your pocket.
Updated on
Mar 21, 2026

Data safety

Safety starts with understanding how developers collect and share your data. Data privacy and security practices may vary based on your use, region, and age. The developer provided this information and may update it over time.
No data shared with third parties
Learn more about how developers declare sharing
No data collected
Learn more about how developers declare collection

Ratings and reviews

3.8
3.94K reviews
David Buckwalter
July 29, 2022
Viewer is great, but doesn't associate file types in the phone's OS. Any time I click on a file to open, it sends me back to the google play store. Instead, I have to open the app and navigate to the file location. This is particularly annoying as a rural user because I'm often out of coverage and the play store won't load. Makes comparing multiple files a significant PITA.
22 people found this review helpful
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Fast STL Viewer
November 26, 2022
Hi David, thank you for the feedback! Could you please test "My Files" again? A Samsung device with Android 13 associates STL files as expected when opening them from "My Files". Thank you!
Steven
March 3, 2025
Overall it served it's purpose, initially. M Then I became more savvy in the art and needed something more than a tool that views and an editor that went more in depth if having to pay. Thank you but unfortunately it's time to move up to another app. Without this app I would have never peaked my interest in this field. A field I now can comfortably say will be my future in all aspects of the term
11 people found this review helpful
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Matthew Conway
March 11, 2026
Was a great app until the Ads become really annoying, I only use the app to view stls and nothing more so the thought of paying £31 a year for that is a joke, if it was £5 a year I'd think about it. I think you over estimate the usefulness of this app. It's a viewer only, anything else is done on a pc.
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Fast STL Viewer
March 11, 2026
Hi Matthew, thanks for the feedback. We show a single video ad per session to support ongoing development and keep the app free — the rest of your session is uninterrupted, even if you switch away and come back. We appreciate you using the app.

What’s new

Open entire assemblies at once — select multiple STL files in your file manager and share them to Fast STL Viewer, or use multi-select in the Open and Add menus.