STL viewer

Open an ASCII or binary STL, rotate its projection and inspect its dimensions.

On your device · No account

Privacy details

STL viewer processes your input in this browser. Inputs and results are excluded from analytics. Recent tools save tool names, visit counts and last-visit times. Saved tools store only their names. Draft saving is optional and stays on this device; delete saved text with the draft controls. Loading text from a URL is optional and contacts that server; its URL and your IP address are visible to the server. An optional “Use in” action keeps a handoff in this tab. The next tool removes it on arrival and ignores it if more than a minute has passed.

Copy link includes the inputs you choose to share in the address. Anyone with that link can reopen them. Files and generated results are excluded. Password and key tools share settings only.

Choose an STL file

Rotate model (degrees)

Reset reloads the tool with its starting values and releases open files and device controls. Saved drafts stay on this device until you delete them.

Links include your inputs and settings. Anyone with the link can see them, so leave out private text. Files and generated results are left out; random draws run again.

Keyboard shortcuts

Updated 2026-09-20

Using the stl viewer

The viewer parses triangle vertices and computes bounds directly from them. The preview is a simple shaded projection with visible edges. Download writes an ASCII STL with normals recalculated from the vertex winding.

Next: Color picker from image

A worked example

The original tetrahedron example has four triangular faces and bounds of 10 × 10 × 10 units.

Before you use the result

STL does not declare units. This viewer supports up to 20,000 triangles and does not establish printability, manifoldness, wall thickness or physical scale.

Next: Image resizer

Cite this page

Citation style

ToolOctopus. “STL viewer.” Updated 2026-09-20. https://tooloctopus.com/stl-viewer.

Add an access date if your instructions require one.

Citation formatting uses citeproc-js by Frank Bennett and Citation Style Language styles. Licence and source code.