Turn an STL into a STEP file you can edit
Found a model you'd love to tweak, but it only comes as an STL? Get a real CAD file you can open and change in your own software.
Runs on a computer, in your browser
Email me the linkParamability runs on a desktop or laptop. Open the app anyway
- Free
- Nothing uploaded
- No account
Will my model convert well?
If it's a mechanical part, most likely yes. Brackets, enclosures, mounts and other parts with flat sides and round holes come out as clean faces you can edit.
Sculpts and figures are a weaker fit: they mostly stay as triangles.
Clean faces
Brackets, boxes, mounts
Mostly triangles
Sculpts and figures
How is this different from other converters?
Most online converters, and the STEP export in many free CAD plans, give you one flat face per triangle. The file opens, but a hole wall is a ring of thin strips, not one round surface you can grab.
By default it splits the model into faces wherever the surface bends sharply, so each flat side, hole wall and rounded edge becomes one face. You can check every face group before you export, tune it, and merge faces by hand for the best result.
One face per triangle
What a typical converter gives you
Grouped into real faces
Each colour is one face
How do I convert an STL to STEP?
Three steps, all in one browser tab.
Open your file
An STL, 3MF, OBJ or another 3D file. Anything you'd send to your slicer works.
Check the face preview
Coloured patches show how the model will split into faces, and a readout tells you how much converts cleanly.
Export
Save one .stp file and open it in your CAD program.
1113 face regions
Flat 89% · Curved 11% · Free-form 0%
Split the model into faces wherever the mesh bends more sharply than the face angleLook over the whole model for planes, cylinders, cones, spheres and blends, and build the faces from what turns up
13 of 13 regions matched a CAD surface
What if some faces come out in pieces?
Sometimes one flat side is picked up as several patches. Turn on Edit regions, click the patches that belong together and press Merge to join them into one face.
1513 face regions
Flat 89% · Curved 11% · Free-form 0%
Click a region · ⌘/Ctrl-click to add or remove · double-click to select every smoothly connected region
What won't it do well?
You get a shape you can edit, not the designer's original steps. It's rebuilt from your mesh, so there's no history to rewind, just surfaces ready to select and adjust.
Sculpts and figures
The file is exact, but large, and many CAD programs open it slowly. To pose or cut a miniature, try the figurine playground.
Big models
Simple parts take seconds. If most of the model has to stay as triangles, past roughly 50,000 of them (a binary STL of about 2.5 MB) a conversion can run for tens of minutes, and the app stops at a set size. Higher detail levels raise that size.
The last resort
If nothing else works, it still converts, as flat triangles you can't do much with.
Quick questions
- Is my file uploaded anywhere?
- No. Everything runs in your browser, and the file never leaves your computer.
- Is it free? Do I need an account?
- It's free, with no account and nothing to install. Open the page, drop your file in and start.
- Can I use it on my phone?
- No, it's made for a computer. Open this page on your desktop or laptop.
- Which files can I convert?
- STL, 3MF, OBJ, GLB and many other 3D formats. If the app can open it as a mesh, it can convert it.
- What if my model is very large or detailed?
- It may need more room. The detail level next to the export button starts at Standard; Extended and Maximum give a big model more headroom, at the cost of a longer wait.
- Can I open STEP files too?
- Yes. Pick Draft, Standard or Fine when one opens, and change it later without reloading the file.
- What about screw threads?
- A printed thread is thousands of tiny triangles. Swap it for the plain cylinder underneath, then cut a fresh thread in CAD if you need one.
- How does it work?
- The app works out which triangles belong to one smooth surface and rebuilds each group as a real face. A full CAD engine runs inside your browser tab.
Bring an STL, leave with a STEP file you can edit.
Runs on a computer, in your browser
Email me the linkParamability runs on a desktop or laptop. Open the app anyway