Free browser STL checker

Check & RepairSTL Files

Check an STL locally, apply conservative low-risk fixes, verify the exact output, and download the repaired file before final slicer validation.

Repair an STL nowPreview the report
Issue families
5
Browser analysis
Local
Verified download
Safe

Free browser STL checker

Check STL mesh health before you slice.

Drop an STL file to check open boundaries, non-manifold edges, normal mismatches, duplicate faces, and degenerate triangles. Safe fixes and verified downloads run locally in your browser.

Anonymous local workflow: up to 10MB or 100,000 triangles. Your STL is not uploaded.

Checks
5 issue families
Privacy
Local first
Repair stance
Safe fixes only
Engine
0.2.0-verified-local-export
Local limit
10MB

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.

Illustrative model photos, not repair evidence. Real checks run locally in your browser.

Faceted owl · duplicate faces
Repeated surface triangles are suitable for a cautious cleanup preview.
Previewed

Faceted owl · duplicate faces

Repeated surface triangles are suitable for a cautious cleanup preview.

Wall hook · facet normals
Mixed facet direction can be reviewed and recalculated without changing the silhouette.
Previewed

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.
Report only

Honeycomb planter · open boundary

Boundary loops remain visible for review instead of being filled automatically.

Score
58 → 58
Issues
12 → 12
Inspect
Turbine shell · non-manifold edges
Shared-edge topology is reported clearly and left unchanged for manual repair.
Report only

Turbine shell · non-manifold edges

Shared-edge topology is reported clearly and left unchanged for manual repair.

Explore repair guides
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 complete
Local mesh preview
Actual STLRepair analysis screen with mesh preview, health score, and five-check matrix
28,442Triangles5Checks run72Health score

Three simple steps

From STL file to readable report

No CAD install and no production file upload are required for the public browser check.

  1. Actual STLRepair upload screen before a local browser check

    Choose an STL

    Drop a binary or ASCII STL into the checker. The public limit is 10 MiB or 100,000 triangles.

  2. Actual STLRepair analysis screen with mesh preview, health score, and five-check matrix

    Analyze locally

    The browser parses triangles, builds mesh topology, and scores five core issue families.

  3. Actual STLRepair repair summary with verified local STL and JSON downloads

    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 issueBrowser checkCurrent repair scope
Duplicate facesRepeated triangles increase file noise and may hide mesh defects.Browser checkReportedCurrent repair scopeSafe preview
Degenerate facesTriangles with near-zero area can confuse slicers.Browser checkReportedCurrent repair scopeSafe preview
Normal direction mismatchesFacet normals disagree with triangle winding.Browser checkReportedCurrent repair scopeSafe preview
Open boundary edgesOpen edges can indicate holes or a non-watertight STL file.Browser checkReportedCurrent repair scopeReport only
Non-manifold edgesEdges shared by too many faces often require manual review.Browser checkReportedCurrent repair scopeReport only

STLRepair previews only low-risk cleanup. Hole filling and non-manifold reconstruction remain report-only and should be reviewed in CAD or a slicer.

Open the checker

Simple, honest pricing

Free local checks. Pay only for server work later.

No account or card is required for browser checks. Private server repair and export will start with pay-as-you-go credits only after delivery is verified.

Local checker

For local STL preflight, diagnostics, and safe repair preview before slicing.

$0 / file

  • Binary and ASCII STL parsing
  • Five core issue families
  • Sampled mesh projection
  • Conservative repair preview
  • No production file upload required
Check a file free

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.

Open STL checker