A good UI Sketch Design Software

In the past, for convenience of communication, we always had to sketch the system interface on paper, which seemed inconvenient for archiving.

Some time ago, I accidentally used the balsamiq mockups software. It feels good. The more times I use it, the better I feel. Haha.

This is: http://balsamiq.com/unfortunately is a paid version, to $79...

However, the design is quite good, such:

 

And this:

 

 

 

This isProgram(The design drawings can also be exported as images, and many formats are supported ):

 

 

 

This software will be available for beginners as soon as they learn it. It may be difficult to change their habits at the beginning.