Faceted owl · duplicate faces
Repeated surface triangles are suitable for a cautious cleanup preview.
Free browser STL checker
Check & RepairSTL Files
Parse an STL locally, flag five core mesh issue families, and preview conservative low-risk cleanup before you validate the file in your slicer.
- Issue families
- 5
- Browser analysis
- Local
- Preview only
- Safe
Original model gallery
Different models. One focused mesh check.
Explore original printable forms across decorative, functional, and mechanical categories, then open the checker for the real local result.
Wall hook · facet normals
Mixed facet direction can be reviewed and recalculated without changing the silhouette.
Honeycomb planter · open boundary
Boundary loops remain visible for review instead of being filled automatically.
Turbine shell · non-manifold edges
Shared-edge topology is reported clearly and left unchanged for manual repair.
- 5
- Core issue families
- 10 MiB
- Public file limit
- 100k
- Triangle limit
- Local
- No production upload
Diagnostic preview
A practical report, not a mystery score
The workbench keeps the mesh view, health score, and five issue families together so you can decide what needs attention before slicing.
phone_stand_sample.stl
Analysis completeLocal mesh preview
Three simple steps
From STL file to readable report
No CAD install and no production file upload are required for the public browser check.
Choose an STL
Drop a binary or ASCII STL into the checker. The public limit is 10 MiB or 100,000 triangles.
Analyze locally
The browser parses triangles, builds mesh topology, and scores five core issue families.
Review and preview
Read the issue list, inspect the sampled projection, and preview only conservative cleanup before slicer validation.
Clear repair boundary
Diagnose first. Repair only what is safe.
STLRepair separates measurable mesh issues, low-risk cleanup, and the checks that still belong in your slicer.
| Mesh issue | Browser check | Current repair scope |
|---|---|---|
| Duplicate facesRepeated triangles increase file noise and may hide mesh defects. | Browser checkReported | Current repair scopeSafe preview |
| Degenerate facesTriangles with near-zero area can confuse slicers. | Browser checkReported | Current repair scopeSafe preview |
| Normal direction mismatchesFacet normals disagree with triangle winding. | Browser checkReported | Current repair scopeSafe preview |
| Open boundary edgesOpen edges can indicate holes or a non-watertight STL file. | Browser checkReported | Current repair scopeReport only |
| Non-manifold edgesEdges shared by too many faces often require manual review. | Browser checkReported | Current repair scopeReport only |
Before you check
What the browser tool does—and does not do
Straight answers about privacy, repair limits, and the role of your slicer.
Does my STL leave the browser?
The public checker parses and analyzes the file locally in your browser. No production-file upload is required for the current check and preview.
Which problems can STLRepair fix?
The current preview can remove duplicate or near-zero-area triangles and recalculate facet normals. Open holes and non-manifold topology are reported for careful manual review.
Do I still need to check the file in my slicer?
Yes. Use STLRepair as a mesh preflight, then confirm scale, wall thickness, orientation, supports, material, and printer settings in your slicer.
Check the file before you spend hours printing it.
Run the free local preflight, review five mesh signals, and validate the result in your slicer before committing material and machine time.