No, they are not the same, and you cannot open one in the other without conversion

Onshape and Inventor are two separate design programs made by different companies. Onshape files use the .part or .assembly format. Inventor files use the .ipt (part) or .iam (assembly) format. If someone sends you an Onshape file and you only have Inventor installed, you cannot open it directly. The same problem happens in reverse.

This matters because many engineering teams use one program or the other, and file format incompatibility can stall a project. You will need either to convert the file, ask the sender to export it in a format both programs read, or use a third program that handles both.

Key Takeaways

  • Onshape files (.part, .assembly) and Inventor files (.ipt, .iam) are native to different programs and do not open in each other.
  • Both programs can export to neutral formats like STEP or IGES, which the other program can then read.
  • Onshape is cloud-based and free for public projects; Inventor is desktop software that requires a paid license.
  • Converting between formats may lose some design history or advanced features, so the converted file may not behave exactly like the original.

Why the formats are different

Autodesk makes Inventor. Autodesk also owns Fusion 360, which is a different program from both. Onshape is made by a separate company called PTC. Because they are built by different teams using different architecture, they store design data in their own native formats.

Inventor stores its data in a way that preserves the full design history — every sketch, every feature, every constraint you made. Onshape does the same thing, but in its own structure. Neither program knows how to read the other's internal format, the same way a Word document will not open in Google Sheets.

What neutral formats do

Both Onshape and Inventor can export to STEP (.step or .stp) and IGES (.iges or .igs) files. These are industry-standard formats that most design programs understand. When you export to STEP, you get a solid 3D model that the other program can read and view.

The trade-off is that STEP exports the finished geometry, not the design history. If you open a STEP file in Inventor, you see the shape, but you cannot edit the original sketches or features the way you could if you had the native .ipt file. You can add new features on top of it, but you cannot go back and change what came before.

For viewing, checking dimensions, or using the model in an assembly, STEP works fine. For collaborative design where both people need to edit the same file, you need both people to use the same program.

When you need to convert

If a colleague sends you an Onshape file and you use Inventor, ask them to export it as STEP first. Most Onshape users can do this in seconds — it is a standard export option in the File menu. You then open the STEP file in Inventor and work from there.

If you are the Onshape user and someone sends you an Inventor file, the same approach works in reverse. Ask them to export as STEP, or if they need you to work in the native Inventor format, you would need to install Inventor or use a conversion service.

Some teams use third-party conversion software like CloudCompare or Fusion 360 (which can read both formats) as a bridge, but for most cases, STEP export is the simplest path.

The difference between cloud and desktop

Onshape runs in your web browser. You do not install it; you log in and design online. Your files live in the cloud. Inventor is desktop software — you install it on your computer, and files normally live on your hard drive or a network folder.

This architectural difference is why the file formats are so different. Onshape was designed from the ground up to work in a browser and sync across devices. Inventor was designed for a single user on a single machine, though it now supports cloud storage and collaboration.

If your team is already in Onshape, switching to Inventor means buying licenses and changing your entire workflow. If your team is in Inventor, moving to Onshape means learning a new interface and migrating projects. File format is only one part of that decision.

What you lose in conversion

When you export Onshape to STEP and open it in Inventor, you lose the parametric history. Parametric means the design is built from rules — if you change one dimension, other parts update automatically. STEP gives you the final shape, but not those rules.

You also lose any custom properties, design notes, or metadata that were stored in the Onshape file. Some advanced features like surfacing details or specific material properties may not translate perfectly either.

For straightforward parts and assemblies, this usually does not matter. For complex designs where you need to edit and re-parametrize, you are better off staying in one program or having the original designer make the changes.

Frequently Asked Questions

Can I open an Inventor file directly in Onshape?

No, not directly. You need to export the Inventor file as STEP or IGES first, then import that into Onshape. Onshape will read the geometry but not the parametric history from the original .ipt file.

Will the converted file look the same?

The shape and dimensions will be the same. The converted file will look identical when you view it. The difference is internal — you lose the ability to edit the original sketches and features that built the design.

Is there a way to convert without losing the design history?

Not between Onshape and Inventor. The only way to preserve full design history is to have both people use the same program. If you need to collaborate across programs, STEP is the standard compromise.

What if I need to edit an Onshape file but only have Inventor?

Ask the Onshape user to export as STEP. You can then open it in Inventor and make changes, but you are working from the final geometry, not the original parametric design. For major edits, it is usually faster to ask the original designer to make the change.

Do I need both programs installed to work with both file types?

No. You can work with STEP files in either program. But if someone sends you a native Onshape or Inventor file and you need to edit it in its original form, you need that program installed or a subscription to use it online.