stepSTLtool
100% Client-SideWebAssembly CAD EngineZero Cloud Uploads.step & .stp

STEP & STP to STL Converter

Convert CAD models locally in your browser. Inspect geometry, verify mesh health, and export Binary STL.

Drop .STEP or .STP file here, or browse

Zero server uploads • Processed locally in browser memory

ISO 10303AP203 / AP214 / AP242Max 250 MB

Tessellation Parameters

Deflection Controls
Draft
0.50 mm
~46° deflection
Standard
0.10 mm
~29° deflection
Fine
0.01 mm
~11° deflection
CAD Workbench
ISO 10303 • WASM
Model Inspection Viewport
Orbit: DragPan: Right-DragZoom: Scroll
CAD Inspection ViewportStandby for model input • Load a STEP/STP file to verify 3D mesh
01
Privacy First

100% Client-Side Privacy

Your CAD geometry never leaves your workstation. OpenCASCADE executes entirely inside a browser-local WebAssembly sandbox.

02
3D Inspection

Model Inspection

Inspect the exact tessellated mesh buffer in 3D before exporting. Toggle wireframe rendering, coordinate axes, and reference grid.

03
Mesh Verification

Mesh Validation

Detect zero-area degenerate triangles, duplicate facets, and non-manifold edges to prevent 3D printer slicing failures.

Dedicated CAD Tools

ISO 10303 Standards
STEP to STL Converter.step
Optimized for standard .step CAD solids
→
STP to STL Converter.stp
Optimized for .stp abbreviated files
→

Frequently Asked Questions

How is StepSTLTools different from online CAD converters?↓

Most online file converters upload your confidential CAD files to remote servers. StepSTLTools executes OpenCASCADE in a local WebAssembly Web Worker on your device, ensuring complete privacy, zero file uploads, and instant 3D inspection.

Which CAD formats are supported?↓

StepSTLTools currently provides dedicated high-precision converters for STEP (.step) and STP (.stp) files to Binary and ASCII STL formats, with real-time 3D verification and topological health checks.

Can I inspect the 3D model before downloading?↓

Yes. The built-in Three.js viewer renders the exact same Float32Array triangle mesh generated by the OpenCASCADE tessellator, allowing you to visually verify curved surfaces and dimensions before exporting.