3dfileconverter.onlineSTL Mesh Checker
Check STL mesh boundaries, non-manifold edges, winding and degenerate triangles in your browser. Review diagnostics locally; this tool does not repair meshes.
Enable JavaScript to open a model and use the interactive workspace.
How do I use this tool?
- Choose an OBJ, STL or STEP model from your device.
- Preview your model and adjust the settings.
- Run checks and review the diagnostics.
What does this tool do?
Checks exact matching vertex coordinates within each part. Reports boundary edges, non-manifold edges, inconsistent winding and degenerate triangles. It does not detect all self-intersections or certify printability.
What are the file limits?
Models are processed locally. Inputs are limited to 50 MB per file and 500,000 triangles after import. Individual operations may have lower limits described below. Performance depends on your device.
JavaScript, WebAssembly and WebGL are required for the interactive workspace.
How are models processed?
Mesh loading and rendering use Three.js. STEP import and tessellation use occt-import-js, based on Open Cascade. These sources describe the underlying libraries; this tool's supported features and limits are listed on this page.
Frequently asked questions
What does this STL mesh checker detect?
It reports open boundary edges, non-manifold edges, inconsistent triangle winding and degenerate triangles. It also calculates surface area and, when the topology allows it, a signed volume diagnostic. Matching uses identical vertex coordinates within each part.
Can the checker repair holes or non-manifold edges?
No. It reports problems without repairing the mesh. Use the results to decide what to fix in a mesh editor, then inspect the revised file again.
Does a clean report guarantee a successful print?
No. These checks do not detect every self-intersection or test wall thickness, supports, material suitability or printer settings. Separate overlapping parts can also require further review.
Why is volume unavailable or negative?
Volume is only shown for closed meshes with consistent winding. Reversed orientation can produce a negative signed value; nested or intersecting shells can make the result misleading. It is a diagnostic, not a certified material-volume measurement.