Free STL Viewer Online

Q: Is this STL viewer really free?

Yes. Every feature is completely free with no account, no subscription and no paywall.

Q: Which file formats are supported?

STL (binary and ASCII), OBJ, PLY, glTF, GLB and 3MF are supported, detected automatically from the file.

Open, inspect and analyze STL, OBJ, PLY, glTF/GLB and 3MF files right in your browser. Rotate in 3D, measure distances, and estimate volume & print weight — no upload, no sign-up, completely free.

Prefer a native app? Get the iOS version for iPhone & iPad.

Everything you need to inspect a 3D model

Many 3D formats

Open STL (binary & ASCII), OBJ, PLY, glTF, GLB and 3MF files. The format is detected automatically — just drop a file and view it instantly.

Full 3D controls

Rotate, zoom and pan. Snap to front, back, side, top and bottom preset views, or switch between perspective and orthographic projection.

Mesh analysis

Estimate volume, surface area and print weight for PLA, PETG, ABS or resin. Check watertightness, open edges and overhang ratio.

Measure distances

Tap two points on the model to measure the straight-line distance in millimeters — great for quick sanity checks before printing.

Customize the look

Pick from preset background and model colors or choose any custom color. Toggle wireframe mode and auto-rotate.

Snapshot & share

Capture the current view as a PNG and download it instantly — perfect for listings, docs and print previews.

100% private

Everything runs in your browser. Your STL files are never uploaded to any server. Free, forever, with no sign-up.

Frequently asked questions

Is this 3D viewer really free?

Yes. Every feature — 3D viewing, measurement, mesh analysis and snapshots — is completely free with no account, no subscription and no paywall.

Are my files uploaded anywhere?

No. freestlviewer is 100% client-side. Your files are read and rendered directly in your browser and never leave your device.

Which file formats are supported?

STL (both binary and ASCII), OBJ, PLY, glTF, GLB and 3MF are supported. The format is detected automatically when you open a file. For glTF, self-contained .glb files work best.

How is volume and weight calculated?

Volume is computed with the signed-tetrahedron method over the mesh triangles, assuming millimeter units. Weight multiplies the cm³ volume by the selected material density (e.g. PLA 1.24 g/cm³) at 100% infill.