What is the best free software for structural modelling?

If you are performing Variance-based Structural Equation Modeling (SEM), then you can explore SmartPLS v2 which is free (but support is ended), suitable for beginners & with visual interface diagramming toolset (see link below).  Latest SmartPLS v3 is not free but have more / improved features vs v2.  For Covariance-based SEM, you can explore R which is free but doesn't have the Graphical User Interface (GUI) you are expecting.  In case you need software with GUI for Covariance-based SEM, you can explore AMOS which is not free or others.

https://www.smartpls.com/smartpls2

What is the best free software for structural modelling?

If you are performing Variance-based Structural Equation Modeling (SEM), then you can explore SmartPLS v2 which is free (but support is ended), suitable for beginners & with visual interface diagramming toolset (see link below).  Latest SmartPLS v3 is not free but have more / improved features vs v2.  For Covariance-based SEM, you can explore R which is free but doesn't have the Graphical User Interface (GUI) you are expecting.  In case you need software with GUI for Covariance-based SEM, you can explore AMOS which is not free or others.

https://www.smartpls.com/smartpls2

Thanks a lot! I think that this information will be very usefull to my researches.

SmartPLS is one of the best free program. But this program predict with PLS algorithym. The other free program is onyx. İt is easy to use and enough for begginers. 

Adress:  http://onyx.brandmaier.de/

Thanks for the information, Özer yılmaz ·. I'm going to study the software.

I am grateful for your rich and detailed answer, Michael R. Frone. I will investigate all your recommendations. Best Regards.