Check an STL Mesh
Check an STL for boundary edges, non-manifold edges, duplicate triangles and winding issues in your browser. Get a report without changing the source mesh.
Supported input and output
Binary and ASCII STL. Report only; source coordinates stay unchanged.
Read issues in the context of your model
A boundary edge belongs to one triangle; a non-manifold edge has more than two incident triangles. Degenerate triangles have zero area, while winding conflicts indicate neighboring faces that disagree in orientation. Separate edge-connected components may be intentional. These checks leave the source unchanged and do not detect every possible solid defect.
How to use this tool
- Load an STL to generate its topology report.
- Inspect boundary, non-manifold, duplicate, degenerate and winding counts; expand details where needed.
- Choose repair or editing only for changes the model actually needs.
Limitations to check
- Edge checks do not detect self-intersections or non-manifold vertex fans. Passing is not a printability guarantee.
- Exact coincident vertices are grouped for analysis. Near vertices remain separate; disconnected components may be intentional.
- Signed volume is an algebraic measurement only for edge-closed, consistently oriented geometry. Nested cavities and intersections are not classified.
File and processing limits
- STL input up to 8 MiB; 150,000 stored vertices and 50,000 triangles.
- Topology analysis: at most 150,000 edge records and 5 million weld comparisons.
- 20 seconds per job; generated STL output up to 3 MiB.
Processing happens in this browser; your file and filename are not uploaded. Cancel, reset or replace the file to stop its worker. Downloads are generated locally.
Questions about this workflow
Does an edge-closed result guarantee printability?
No. Self-intersections, non-manifold vertex fans, nested cavities, wall thickness and printer constraints are not all checked. Treat the report as diagnostic evidence alongside inspection in your slicer.