Free tool · STEP, STP, STL, and OBJ · No registration
STEP viewer. Measure, weigh and analyze your part.
Open your 3D file in the browser, without installing anything. In a STEP you measure edges, diameters and distances; in any format you see the dimensions, the volume and what the part weighs in the material you choose. And with the manufacturability check, whether it can be machined.
Drag and drop your 3D file here
Or choose it on your computer. One part per file; we don't store anything.
Preparing the viewer…
Reading the file…
Analyzing the STEP geometry…
Converting the OBJ…
Sample part
Solids
Faces
Triangle mesh
Solid part
Open my file
Open another file
A mesh has no edges to measure. To measure diameters and distances, open the STEP.
The mesh is not closed: volume and weight are not reliable.
Measures less than 3 mm. If the file is in inches or meters, change the units.
Measures more than 3 meters. If the file is in another unit, change it.
The viewer opens STEP, STP, STL, and OBJ. Export the part from your CAD to one of these formats, preferably STEP.
The file is empty.
The STEP file exceeds 10 MB. Remove unnecessary details for manufacturing or upload the part directly to the quoting platform.
The file exceeds 60 MB. Export it with lower resolution or in STEP format, which takes up much less space.
The file is not a valid STEP. Re-export it from your CAD software.
We were unable to connect to the STEP analysis server. Please try again in a few minutes.
The analysis took too long. If the part is very complex, simplify it or request the quote directly.
You have analyzed many files in a row. Please try again in an hour.
The page has been open for too long. Refresh it and try again.
The geometry is too heavy for the STEP viewer. Upload it to the quote platform and we will review it.
The STEP viewer could not be loaded. Check your connection and reload the page.
We were unable to read the part. Please re-export it from the original model and try again.
There are several parts in the file: the volume and weight are for the assembly. To request a quote, export each part in its own STEP file.
The file contains no solids: it may only contain surfaces or a 2D drawing.
The part has open surfaces: it is not a closed solid.
The STEP file carries a mesh, not a solid: it is suitable for 3D printing, not for CNC machining.
The geometry has errors, such as intersecting faces. Fix it in your CAD software and export it again.
Preparing the manufacturability check…
The manufacturability check could not be loaded. Check your connection and try again.
Metals
Plastics
High-performance engineering plastics
3D printing MJF
Vacuum casting
Rotate
Distance
Edge and Ø
Clear
Rotate, zoom, and pan the part
Click two vertices and it will show the distance
Click an edge: length, radius, or diameter
Clear all measurements
Double-click on the part: rotates around that point.
Double-click outside the part: returns to the center.
Scroll wheel: zoom in and out. Right button: pans.
Loading the part…
Arc
Chord
We couldn't render the part. Re-export it and try again.
- Dragrotates
- Wheelzooms
- Right-clickpans
- Double-clicksets the pivot
- One fingerrotates
- Pinchzooms
- Two fingerspan
Your file is not stored. STL and OBJ files are read in your browser and never leave your computer. The STEP file is sent encrypted to our CAD analysis server, which converts it for display and measurement, then discards it. Data protection
01 / What it does
What you see in the CAD,
without opening the CAD.
To review a file sent to you, display a part in a meeting, or check dimensions before requesting a quote.
All views, with one click
Drag to rotate and use the scroll wheel to zoom in. The view cube takes you to front, top, or right with SolidWorks names, and double-clicking sets the center of rotation where you need it.
Exact geometry
Real edges come from the STEP. Click a circle and it gives you the diameter; a line, its length; two vertices, the distance between them. In millimeters and with two decimals.
Volume, surface area, and weight
The volume is that of the solid, not the box. Choose the material and the viewer multiplies it by its density: the example support weighs 369 g in aluminum and 1.07 kg in steel.
How much is removed as chips
The bounding box is the block from which the machined part would be produced. If the milling tool has to remove more than three-quarters, ask us about sheet metal cutting and bending, 3D printing, or vacuum casting: it might be cheaper.
02 / Formats
STEP, STL or OBJ.
They don't store the same data.
The viewer opens all three, but only STEP describes the part exactly as you drew it. For manufacturing, use STEP.
| STEP · STP | STL | OBJ | |
|---|---|---|---|
| What it stores | The exact solid: faces, edges, and cylinders (B-rep) | A mesh of triangles | A mesh of polygons, sometimes with color and texture |
| Units | Inside the file | It does not store them: they are assumed to be in millimeters | It does not store them |
| Measure edges and diameters | Yes | No | No |
| Volume and weight | Exact | Approximate, if the mesh is closed | Approximate |
| For manufacturing | CNC machining, sheet metal, casting, and 3D printing | 3D printing only | Convert it to STEP or STL first |
| Where it opens | On our CAD analysis server, without storing it | In your browser | In your browser |
STEP and STP are the same standard, ISO 10303-21, with two extensions. Versions AP214 and AP242, which almost every CAD program exports, both work.
03 / Export
Export a STEP
from your CAD.
In all programs, it is under Save As or Export. One part per file, without fasteners or assembly parts.
SolidWorks
File › Save As, and in the type choose STEP AP214 or AP242 (*.step).
Autodesk Fusion
File › Export › STEP. If the design has multiple bodies, export each part in its own file.
Inventor
File › Save As › Save Copy As, and choose STEP files (*.stp).
Onshape
Right-click on the part, in the parts list › Export, with STEP format.
CATIA, Creo, and Solid Edge
Save As (in Creo, Save a Copy) and choose the STEP or STP type.
FreeCAD and Rhino
Select the solid and use Export (in Rhino, Export Selection) with STEP format.
SketchUp and Blender
They work with meshes and do not export STEP by default. For 3D printing, the STL is sufficient; for machining, the part has to be modeled in a solid-modeling CAD program.
Native format
To request a quote, we also accept SLDPRT, X_T, X_B, IPT, CATPART, PRT, SAT, and 3DM. The viewer opens STEP, STL, and OBJ.
04 / Before ordering
Four warnings
that save a round trip.
The STEP analysis detects what later hinders a quote. If any appear in the panel, correct them in your CAD before uploading the part.
Multiple parts in a file
Two loose solids are not quoted as one, and the weight shown is for both. Export each part in its own STEP.
Open surfaces
If a face is missing, the part is not a closed solid: there is no volume or weight, and machining does not know where the material is. It usually comes from converting from another format.
A mesh inside the STEP
A STEP made from an STL remains a mesh: flat facets where cylinders were. It works for 3D printing, not for machining a housing.
Invalid geometry
Faces that cross or edges that do not close. It can almost always be fixed by redoing the failing operation or exporting again from the original model.
05 / Manufacturability check (DFM)
Can it be machined?
The viewer tells you.
DFM means design for manufacturing: reviewing the part before making it. Open your file and click "Check manufacturability": within seconds you see it marked in red and orange, with the reason and what to change.
What the analysis checks, rule by ruleWhat won't come off the machine
A sharp internal corner, a 0.4 mm slot or an undercut no end mill can reach, not even on 5 axes. It can't be machined like that: the design has to change.
What can be made, at a cost
An R0.5 radius in a 12 mm deep pocket needs a Ø0.8 end mill working at more than 15 times its diameter: more passes and more time. With R1 it's already fine.
Depth, bottom and edges
A blind hole up to 6 × Ø is done with a standard drill, and up to 20 × Ø with a long drill. It also checks the shape of the bottom and whether the hole cuts the edge of the part.
Tells turning from milling
It recognizes turned parts and analyzes them as such: a Ø4 shaft 70 mm long is flagged because it bends under the tool.
06 / Frequently asked questions
STEP files,
what we are asked about most.
Twelve short answers. The rest, in the FAQ.
View all questionsHow do I open a STEP file without installing any program?
Drag it to this viewer or click "Choose file". In a few seconds you have the part in 3D: you can rotate it, measure its edges, and view the volume, surface, and weight. It works on Chrome, Edge, Firefox, and Safari, as well as on mobile.
What is the difference between a STEP file and an STP file?
None. They are two extensions of the same format, the ISO 10303-21 standard. Only the file name changes, not its contents, and the viewer opens both.
Is the viewer free? Do I need to register?
It is free and requires no registration. We made it so you can review your parts before requesting a quote, or to open a STEP sent to you without having CAD on hand.
Is my file saved when I open it in the viewer?
No. STL and OBJ files are read in your browser and do not leave your computer. The STEP file travels encrypted to our CAD analysis server, which converts it to a mesh for rendering, calculates edges, volume, and surface, and discards it upon completion. It is also not added to any quote request: to get a quote, upload it to the platform.
Why can't I measure diameters in an STL?
Because STL does not save edges or circles, only triangles: a 25 mm hole is a polygon with many sides, and its diameter depends on where you measure. STEP preserves the exact geometry, and with it the viewer measures diameters, radii, and distances to two decimal places.
How does it calculate the part weight?
It multiplies the solid volume by the density of the material you choose. It is the weight of the solid part: the example support, 136 cm³, weighs 369 g in aluminum and 1.07 kg in carbon steel. In MJF printing, parts also come out solid, so the calculation is the same.
Why does my part come out 25 times smaller?
Because the STL is in inches and it has been read in millimeters: an inch is 25.4 mm. STL does not state in which units it was exported, so the viewer assumes millimeters; change them in the panel. In a STEP, the units are inside the file and no problem occurs.
How much space can the file occupy?
Up to 10 MB in STEP and 60 MB in STL or OBJ. A STEP that weighs more usually carries detail that is not needed for manufacturing, such as threads modeled thread by thread, raised text, or assembly fasteners. Remove it or upload the part directly to the quoting platform.
Can I open an assembly?
The viewer opens it, but it warns you that there are several parts, and the volume and weight are those of the assembly. To request a quote, each file must carry a single part: export each one in its own STEP.
Can a STEP be opened in SketchUp, Blender, or AutoCAD?
AutoCAD imports it as a solid. SketchUp and Blender work with meshes and need a plugin to read STEP. If you only want to view the part, measure it, or show it, this viewer is faster than installing anything.
What is a manufacturability check (DFM)?
DFM stands for design for manufacturing: reviewing a part so it can be made without surprises. The viewer does it for CNC machining: it measures internal radii, walls, slots, holes and areas with no access, and marks in red what can't be machined and in orange what makes it more expensive.
How do I know whether my part can be machined before requesting a quote?
Open it in the viewer and click "Check manufacturability". If nothing shows in red, it can be machined as it is; what shows in orange can be made, but changing it lowers the price. It is free and the file is not stored.
Design ready?
Upload your file
and get a quote.
Upload your 3D model to the Proto&Go! platform, choose process, material, finish, and quantity. You'll receive the quote in 24 hours.
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