Convert JT to STP in your application
3D InterOp is a CAD interoperability SDK that lets your software read JT files and write STP, carrying across the exact geometry the JT file contains.
Spatial does not offer an online converter or a desktop conversion app. 3D InterOp is a component that software vendors embed in their own products.
- Reads JT · Writes STEP
- Mixed geometry → exact geometry
- C++ / C# APIs
JT to STP at a glance
JT can mix exact solids and facets; STEP stores exact geometry. Exact elements are written as exact geometry, and elements stored only as facets stay faceted.
| JT (source) | STEP (target) | |
|---|---|---|
| Full name | Jupiter Tessellation | Standard for the Exchange of Product model data |
| Standard / owner | Siemens, ISO 14306 | ISO 10303 — AP203, AP214, AP242 |
| File extensions | .jt | .stp, .step |
| Geometry | Tessellated and/or exact B-Rep | Exact B-Rep |
| Assemblies / structure | Yes | Yes |
| PMI | Semantic and graphical | Graphical and semantic (AP242) |
| 3D InterOp support | Read only | Read and write |
What's preserved, what changes
Here is what your application can expect to carry across from JT to STEP.
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Preserved
Exact geometryExact B-Rep read from JT is written to STP as exact geometry.
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Preserved
Product structureThe JT product structure is written to STP.
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Changes
Faceted partsParts the JT file stores only as facets are written as facets.
Why software vendors add JT to STP conversion
Supplier and OEM exchange
STEP is the ISO standard most supply chains specify for exchanging 3D models. Writing it lets your users send data to partners on any CAD system.
Model-based definition
STEP AP242 can carry semantic PMI next to exact geometry, so your users can share models together with their manufacturing data.
Long-term archiving
As an ISO standard independent of any CAD vendor, STEP is widely used to archive product data.
Things to check before you ship
- Written STP versions: AP203, AP214 or AP242 (.stp, .step or .stpx).
- Semantic PMI in STEP AP242 needs a license in addition to the STEP writer.
- Supported JT input: JT 8.x to 10.3 and 10.5 to 10.11.
- Test PMI transfer end to end with real JT files from your users.
- Validate a sample of translated files in the target system your users actually work with.
Working with Spatial was a real milestone for us: Thanks to the powerful 3DInterOp library, we were able to successfully bring our complex CAD-based solutions to the cloud while remaining flexible to meet individual customer requirements. For us, Spatial is not just a technology partner, but a true enabler of our product strategy.
Dr. Arno Michelis, Founder, Simus Systems
Read the Case StudyAbout the formats
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Source format
What is a JT (.jt) file?
JT is Siemens’ lightweight format for visualizing and sharing 3D product data, published as ISO 14306. A JT file can hold tessellated levels of detail, exact B-Rep, product structure and PMI.
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Target format
What is a STEP (.stp) file?
STEP is the ISO 10303 standard for exchanging 3D product data between CAD systems. Its application protocols range from exact geometry (AP203, AP214) to full model-based definition with PMI (AP242).
Frequently asked questions
The exact B-Rep that 3D InterOp reads from JT is written to STP; parts stored only as facets stay faceted.
3D InterOp reads PMI from JT, and semantic PMI can be written to STEP AP242 with the additional STEP AP242 license.
Yes. 3D InterOp reads the JT product structure and writes it to STP.
The STEP writer supports AP203, AP214 and AP242, with AP214 as the default. Your application sets the version at export; semantic PMI is written to AP242 only.
Yes. 3D InterOp imports several levels of detail and the visual materials of JT files.
3D InterOp reads JT 8.x to 10.3 and 10.5 to 10.11.
No. 3D InterOp reads JT but doesn’t write it. To send data back, write a neutral format such as STEP.
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Building software that needs to convert JT to STP?
3D InterOp is an SDK that lets your application read JT and write STEP alongside 30+ CAD and BIM formats.