Convert STL files between readable ASCII and compact binary. Compare source and actual output previews, file sizes and coordinate rounding before downloading.
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ASCII or binary STL, up to 20 MiB and 100,000 triangles. Output is also limited to 20 MiB. WebGL 2 is required for source and converted previews.
Choose an STL to begin.
Conversion retains triangle order and winding, not source headers, names, color attributes or solid grouping. Normals are recalculated. Binary coordinates use float32; the result report shows rounding changes. No repair or unit conversion is performed.
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Source preview will appear here.
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Choose an output encoding and convert to preview the generated STL.
The previews can be orbited and zoomed independently. Use their Full screen buttons for a larger view. Both previews are fitted for display; the output retains original coordinate placement. STL declares no physical units. The converted preview is rebuilt from the generated STL bytes. Neither conversion nor a successful preview certifies printability.
Your STL stays on your device. Parsing, serialization and both 3D previews run entirely in your browser using self-hosted code. No account, server upload or source-file history is needed.
Triangle order and winding are retained, but source headers, names, multiple-solid grouping, color and attribute data are discarded. Normals are recomputed. ASCII decimals are parsed as JavaScript numbers; binary output rounds coordinates to float32. The report counts rounded coordinate values and gives the largest absolute change.
No. Binary STL has 84 bytes of header/count plus 50 bytes per triangle. ASCII size depends on the written numbers. The tool compares actual sizes rather than promising a reduction.
The converted STL bytes are parsed again and verified before preparing the output preview. Original coordinate placement is preserved in the file; each preview is independently fitted for display. WebGL 2 is required for these previews and download readiness.
One standard ASCII or binary STL up to 20 MiB and 100,000 triangles, with a 20 MiB output limit and bounded worker/preview timeouts. Large ASCII exports may exceed the output limit. This tool does not repair meshes, certify printability, convert units or preserve source metadata. Zero-area output triangles are reported, not removed.
