JT Assistant

Open CASCADE JT Assistant


OPEN CASCADE JT Assistant is a viewer for files in JT format, an industry focused, high-performance, lightweight, flexible file format intended for representation of 3D products. JT files can contain assemblies of industrial scale (up to 100 000 parts).

JT Assistant handles JT meshes and supports late loading, CPU based size and visibility filtration techniques to optimize the amount of loaded and visualized data, as well as level-of-detail (LOD) management.

It has been developed as a visualization and testing platform for Open CASCADE JT supporting tools. OPEN CASCADE JT Assistant is intended to be a basis for development of custom applications dealing with JT data format for CAD/CAM/CAE products presentation and processing.

Open source publication

JT Assistant is published under a double license: GNU GPL v2 and a Commercial license for those looking to incorporate this software into their own business.

Please visit the source repository page to access sources and installation instructions.

Please contact us for information on the commercial license and possible integration in your applications.

Supported JT data

JT file versions 8.0 - 9.5 are currently supported. Mesh data and assembly structure are visualized. Monolithic and non-monolithic assemblies are supported.

OCCT Carter model (converted to JT) in JT Assistant

Assembly structure of the model can be navigated through the tree browser, displaying the names of parts and their instances in the assembly (if available). Assembly components can be hidden or shown as necessary to inspect the model.

Navigation and selection in the assembly structure

View operations

JT Assistant 3D viewer provides intuitive manipulation of the view by mouse and wheel. The view parameters and controls to manipulate the view can be customized in user preferences.

A toolbar provides buttons for fitting a model to the window and a choice of standard views. Settings are available in a dedicated tab and provide access to the viewer and application options.

Supported platforms

Windows and Linux (32 and 64 bits) platforms, as well as Android platform are supported.

Sample models

You can find sample JT files at:

Development and support

OPEN CASCADE will continue development of JT Assistant, improving its performance and adding new features.

Please contact us if you have ideas how to improve the application or wish to use this technology for development of customized solutions for your business.

Use the Forums to post your comments; your feedback is always welcome! We will appreciate users sharing their experience of using the application on particular devices.


The application is provided AS IS, without warranty of any kind.