Finding 01 · Check before export
Duplicate faces
Can usually be removed without changing intended shape.
Safe preview
Online STL repair workspace
Run an STL repair check online before opening a slicer.
Upload a small STL file in the browser, inspect mesh health, preview safe fixes, and see which geometry still needs manual review.
- Browser-local V1 check for anonymous files
- Safe repair preview before paid export
- Report-only labels for risky topology
Check STL onlineBrowser-local first pass
Diagnostic bench
Upload an STL for online repair triage
Start with a local mesh check for open-boundary hole signals, non-manifold edges, duplicate faces, degenerate triangles, and normal mismatches.
Check STL online42
Finding 02 · Critical review
Open boundary edges
Flagged as possible holes; not guaranteed watertight repair.
Report only
Inspection focus
Best for online pre-slicer checks
Use this page when the search intent is “can I repair this STL online without installing another mesh tool?”
- Separate safe fixes from geometry that needs a modeling tool.
- Check whether the model is likely non-watertight before slicing.
- Keep the first pass fast and local for small files.
Repair boundary
Online repair boundary
The online workflow previews conservative repair actions. It does not promise a guaranteed print-ready file.
Supported
- Remove degenerate faces
- Remove duplicate triangles
- Recalculate facet normals
Report only
- Complex non-manifold topology
- Unsupported hole filling
- Thin walls or slicer-specific printability
FAQ
Questions before the next print
Can STL Repair fix every STL online?
No. It previews safe fixes for common mesh issues and keeps open boundaries or non-manifold geometry report-only when manual review is safer.
Does the online checker upload my file immediately?
Anonymous checks run locally in the browser. Saving private reports or server-created repair artifacts requires sign-in.
What should I do after the online report?
Review the issue list, run the safe repair preview, then validate scale, orientation, and slicer settings before printing.
Related diagnostics
Continue the diagnostic path
01
Fix STL File Issues
Find why an STL file fails in a slicer and preview safe fixes for duplicate faces, degenerate triangles, and normal mismatches.
02
STL File Repair Reports
Generate an STL file repair report with issue severity, safe repair actions, before/after deltas, and export boundaries.
03
Free STL Checker
Upload an STL file to check mesh health, open-boundary hole signals, non-manifold edges, triangle counts, dimensions, and repairability.