Repair STL Online — Fix Non-Manifold Edges & Holes, No Upload | Layerpaint
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Free · No upload · No size cap

Repair an STL in your browser

Drop an STL, OBJ or 3MF and get a diagnosis: non-manifold edges, holes, flipped normals, degenerate triangles, shells. One click repairs what can be repaired — with before/after numbers, not a vague "fixed!". Nothing is uploaded.

Drop an STL, OBJ or 3MF here

or choose a file — it gets checked for the defects slicers complain about, then repaired.

.STL · .OBJ · .3MF · limited only by browser memory
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Diagnosis

not watertight
File—
Triangles—
Size—
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Reading file…

Repaired and ready to paint? Open the same model in Layerpaint, color it per region, and export a Standard 3MF your slicer prints in multiple filaments.

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🔒 Files are processed locally in your browser and never uploaded.

Mesh repair without the upload

The usual routes to a fixed STL have all narrowed. Bambu Studio's built-in repair is Windows-only. Meshmixer is discontinued. The web services that remain want your file on their server, cap the size, or meter the repairs. This tool runs the whole thing in your browser: the mesh is parsed, analyzed and repaired on your device, so a 100 MB scan is fine, a confidential client model is fine, and there's nothing to sign up for.

What gets diagnosed — and what gets fixed

The diagnosis counts the defects slicers actually complain about: non-manifold edges (an edge shared by three or more triangles — usually a zero-width flap pinched against the surface), open edges (holes and cracks), inconsistent winding (flipped normals), degenerate triangles and duplicate geometry, plus the shell count. The repair drops flap faces, closes holes and cracks by fan-filling their boundary loops, makes the winding consistent, and turns inside-out shells right side out. Vertices are never moved, so the shape you drop is the shape you download.

Intentional openings are respected: a hole is only closed automatically when it's small relative to the model, so an open-bottom figure or a vase keeps its opening. If you actually want the big opening sealed — a scan with a missing base, say — tick close big openings too before repairing.

An honest report, including when it can't fix everything

Every repair shows before/after counts per defect. When something remains — heavily self-intersecting geometry, fragments that don't form a closed loop — the report says exactly what's left rather than pretending. Meshes like that need manual editing in a mesh tool; knowing that after ten seconds in a browser beats discovering it after a failed print.

Painted files keep their paint

Drop a painted 3MF and the per-face colors ride through the repair — surviving triangles keep theirs, patch triangles take the color at the hole's edge. Download as 3MF to keep the paint, or as STL/OBJ if you just need clean geometry.

Questions

Is my model uploaded anywhere?
No. Everything — parsing, analysis, repair, writing the output — happens in your browser. The only size limit is your machine's memory.
What does the repair actually fix?
Non-manifold edges, holes and cracks, flipped/inconsistent winding, inside-out shells, degenerate triangles and exact duplicate geometry. Big openings are left alone unless you opt in to closing them.
Can every mesh be repaired automatically?
No — and the before/after report says so when it can't. Self-intersecting or fragmented geometry can need manual work in a mesh editor. Nothing hides behind a success message.
Does repairing remove the colors from a painted 3MF?
No. Per-face paint carries through the repair; patches inherit the color at the hole's edge. Download as 3MF to keep it.
Will the repaired file slice cleanly?
That's the point of the pass — it's the same class of repair slicers run internally. The watertight badge tells you whether the mesh ended fully closed; if defects remain, they're listed.