One tool that I've been using is called Pygubu. It's open source and can be run anywhere python is installed. It includes support for not only Python version 3 but also version 2 as well. It appears to be an active and popular project and includes documentation too.

Pygubu (open source)

Pygubu is a RAD tool to enable quick and easy development of user interfaces for the Python's tkinter module.

 

The user interfaces designed are saved as XML files, and, by using the pygubu builder, these can be loaded by applications dynamically as needed.

 

Pygubu is inspired by Glade.

One tool that I've been using is called Pygubu. It's open source and can be run anywhere python is installed. It includes support for not only Python version 3 but also version 2 as well. It appears to be an active and popular project and includes documentation too.

Pygubu (open source)

Pygubu is a RAD tool to enable quick and easy development of user interfaces for the Python's tkinter module.

The user interfaces designed are saved as XML files, and, by using the pygubu builder, these can be loaded by applications dynamically as needed.

Pygubu is inspired by Glade.