# STL Viewer

> Loft STL Viewer is a free online STL file viewer that opens binary and ASCII STL files in your browser without any upload, install, or signup. It renders the mesh in a Three.js orbit scene, supports shaded / wireframe / shaded + edges display modes, measures distance in millimetres between two surface points, and exports a PNG screenshot. Opens STL files exported from Prusa, Bambu, Cura, and other slicers, or any CAD package such as SolidWorks, Fusion 360, or Blender. Files never leave your device.


Live tool: https://lofttools.com/tools/open-tools/stl-viewer

Category: Open Anything


## What it does

- Binary and ASCII STL parsing
- Three.js WebGL2 renderer with orbit, pan, zoom
- Shaded, wireframe, and shaded-with-edges render modes
- Point-to-point measurement (click two surface points; distance in model-space units)
- Reset-camera button frames the mesh in one click
- PNG screenshot export
- Drag-drop or file-picker input
- Triangle count + file size in the status footer
- WASM CAD kernel wired and reported in the status footer (full B-rep STEP coming in a later release)
- Works offline after the first visit (PWA cache)

## How it works

1. **Drop your STL file** — Drag any binary or ASCII .stl into the browser, or click Open and pick one. The model loads instantly — nothing leaves your device.
2. **Orbit and inspect** — Drag to orbit. Right-click drag (or two-finger drag on a trackpad) to pan. Scroll to zoom. Switch between shaded, wireframe, and shaded-with-edges modes.
3. **Measure** — Click Measure, then click two points on the surface. Distance shows in the status bar in the file's native units (usually millimetres).
4. **Screenshot** — Click Screenshot to download the current view as a PNG.

## FAQ

### What STL formats are supported?

Binary and ASCII STL. Files of either flavour open the same way — the viewer detects the format automatically.

### Will my file leave the browser?

No. Parsing and rendering happen in your browser tab. Nothing is uploaded to a server.

### Does it support OBJ, PLY, GLB, or 3MF?

Yes. Drop any OBJ, PLY, GLB, glTF, or 3MF file — the viewer auto-detects the format. Separate landing pages exist at /tools/open-tools/obj-viewer etc for each format's SEO.

### What about STEP / IGES / DWG?

STEP support is in active development — Loft's CAD engine is being built specifically for it. IGES and DWG are out of scope for the browser viewer; convert upstream to STEP or GLB.

### Why does the engine version show in the status bar?

The viewer loads our in-browser CAD engine (Rust → WASM) and surfaces its version as a wire-contract check. The full B-rep STEP pipeline that engine drives ships in a later release; the STL path you're using today is pure JavaScript.

## Tips

- **Right-click drag to pan** — Left-click drag orbits, right-click drag pans, scroll zooms. Hold Shift for fine orbit control on detailed parts.
- **PNG snapshot at any size** — Click camera icon to capture the current view. Choose resolution up to 4K — handy for slide decks and emails.
- **Confidential CAD stays local** — STL bytes load straight into WebGL — nothing reaches a server. Open client files on shared or hotel computers safely.

## How Loft STL Viewer compares

| Tool | Install needed | Files uploaded | Binary STL | ASCII STL | Measurement | Cost |
| --- | --- | --- | --- | --- | --- | --- |
| Loft STL Viewer | No | No (in-browser) | Yes | Yes | Point-to-point | Free |
| Microsoft 3D Viewer | Yes (Windows) | N/A | Yes | Yes | No | Free |
| viewstl.com | No | Yes (server upload) | Yes | Yes | No | Free |
| online-3d-viewer.com | No | Yes (server upload) | Yes | Yes | No | Free |
| MeshLab | Yes (desktop) | N/A | Yes | Yes | Yes | Free |
| PrusaSlicer / Cura | Yes (desktop) | N/A | Yes | Yes | Yes | Free |

_Verified 2026-05. Browser viewers usually upload — Loft's runs entirely in your tab, no server round-trip.
_

## Privacy — what we do not do

This tool runs entirely in the browser via WebAssembly. Your file never reaches a Loft Tools server. Specifically:

- **No upload.** The file bytes load into the browser tab's memory and process on your own CPU. Open DevTools → Network and observe zero outbound requests carrying file data while STL Viewer runs.
- **No AI training on your file.** Loft does not train models. We could not train on a file we cannot see.
- **No content scanning.** No virus, copyright, or content-moderation pass against your file. The bytes are not accessible to us.
- **No server-side log of file contents, filenames, or EXIF metadata.** Cloudflare edge captures URL and truncated IP for abuse defense (standard CDN behaviour). Cloudflare Web Analytics records anonymous page hits, no cookies, no PII. Nothing about your file content reaches any log.
- **No retention.** Close the tab and the file leaves browser memory. No backups exist on our side because no copy ever existed on our side.
- **No account.** No email, no signup, no auth, no telemetry tied to you.
- **Offline-capable after first visit** (PWA). Once you've loaded a tool, it caches; later sessions work without internet. For high-sensitivity files, run the tool once online to warm the cache, then disconnect before processing.

Compare with upload-based services: each transmits your file to a processing server. Even over HTTPS, each has logs, retention windows, and subpoena exposure. Loft has none of these because the server architecture does not include your file.

## More

- All tools: https://lofttools.com/tools
- Category: https://lofttools.com/tools/open-tools
- LLM index: https://lofttools.com/llms.txt