At Balsamiq we are big fans of open source software. We use a lot of it to power our business and our infrastructure, and we try to give back to the open source community whenever we can.
We open source parts of our code and tools, usually with MIT licensing. Visit https://github.com/balsamiq to find out more.

The Balsamiq Sans font
We also open-sourced the font we created for Balsamiq Wireframes. It's called Balsamiq Sans, check it out!