Free STL repair, in your browser

Yes. Open MeshNomics in your browser and choose an STL, 3MF or OBJ file. The free tool checks the mesh and repairs supported defects without an account or uploading the model. It cannot fix every file. Review any unresolved findings, then check the exported file in your slicer before printing. Usage metadata, when enabled, is explained beside the file picker.

Reversed faces are triangles facing the opposite way from their neighbours. The repair pass makes face winding consistent and can turn an inside-out surface right side out. Other defects can still prevent a valid result. Review the after-state and export checks, then reopen the output in your preferred slicer to check its scale, layers and remaining warnings.

The tool can cap small holes with flat, convex rims using their own boundaries. Large, concave or twisted openings are left open and named rather than filled with guessed geometry. If a hole remains, edit the source model or use a specialist repair tool, then inspect it again. A closed mesh alone does not prove the part will print correctly.

Non-manifold edges occur when more than two faces share an edge. MeshNomics diagnoses them but does not repair them: there is no single safe way to choose the intended surface. Review the report, correct the topology in the source CAD or a specialist mesh editor, then scan the revised file. Do not treat an unresolved finding as a successful repair.

Three causes, and the audit distinguishes them. The surface may be inside out, so it encloses a negative volume. It may be open, in which case there is no well-defined inside at all. Or it may hold separate shells that disagree about which side is solid, whose signed volumes cancel — which produces a confident, meaningless figure. In that last case the number is withheld rather than shown, because a wrong volume becomes a wrong filament cost and a wrong price.

Not necessarily — plenty of models are genuinely several parts. The tool counts the shells and tells you how many there are. It does not merge them: if they are meant to be one solid, that needs a boolean union, which is real computational geometry rather than something to approximate on a mesh somebody is about to print.

It is a surface that passes through itself. The scan searches for them and reports how many pairs of triangles it found; it never repairs them. Resolving one means re-cutting and re-stitching geometry. On a very large model the search can run out of budget, and when it does the tool says the defect is neither ruled out nor fixed rather than reporting the file as clean.

No model file or filename is uploaded. Repair runs inside this tab. When usage reporting is enabled, opening the tool records a random visit ID and referral/campaign information. Scanning records a geometry fingerprint, format, byte size and diagnostic counts even without a repair. Repair events add geometry measurements, actions and print-readiness settings; download requests and any print outcomes or notes you submit are also recorded. This metadata is stored in our database (providers are listed in the privacy policy at /privacy) and readable only by authorized MeshNomics administrators. See the usage-data disclosure beside the file picker for the current reporting status. Local repair works even if reporting is unavailable.

STL in both binary and ASCII, supported 3MF projects, and OBJ. Available exports are 3MF, binary STL and ASCII STL, subject to the repair and export checks. A rebuilt 3MF is not an exact copy of the original project; review the export panel for preserved settings and anything omitted. Unsupported or oversized input is reported, not silently certified.

There is no server-side queue: processing runs in your browser. The triangle limit is 1,500,000, and browser memory plus 3MF archive and component limits also apply. Processing time depends on your device and model. Some checks, including the self-intersection search, have work budgets; unfinished checks are labelled, not counted as passed. You can cancel a running job.