Turn a triangle mesh into a real CAD solid. Our engine recognizes planes and cylinders and rebuilds them as true analytic CAD surfaces — a plate with two holes converts to exactly 8 faces, same as native CAD, not 500 triangles. Every job reports the method used, face count and volume accuracy.
An STL is just triangles — no surfaces, no features, no topology. Most free converters wrap every triangle as a tiny CAD face and call it done: the file opens, but with 50,000 faces your CAD grinds and editing is hopeless.
StlWiz reconstructs geometry in three tiers, best first: analytic recognition detects planar and cylindrical regions and rebuilds them as true CAD surfaces — holes become real cylinders with exact circular edges, so a machined plate converts to the same handful of faces native CAD would produce; coplanar merging handles what recognition can't; a faceted fallback guarantees you always get a valid solid. Every result is verified as a closed solid with volume checked against your mesh — if quality gates fail at one tier, we drop to the next instead of shipping garbage. Benchmarks: a plate with two holes converts to exactly 8 faces (native-CAD parity); volume preserved to 99.98%.
Heads-up on expectations: organic sculpts fundamentally can't become tidy parametric CAD — that's true of every tool. For mechanical parts, this is as clean as web converters get.
STEP is the format every CAD package agrees on, which is why STL to CAD, STL to SolidWorks and STL to Inventor all come down to the same conversion. Once you have the STEP, use File → Open (not Insert → Mesh) in SolidWorks, Upload in Fusion 360, or plain Open in FreeCAD, Inventor, Rhino, Onshape and Solid Edge — each imports it as a solid body you can measure, section and boolean against.
Your CAD may write the file back out as .stp. That is the same ISO 10303 format under a shorter extension — SolidWorks and Siemens NX prefer .stp, most other tools prefer .step, and nothing about the contents differs. Going the other direction is on our STEP to STL converter.
Every converter runs the same geometry engine — see all 20 conversions.