Balsamiq Sans is the handwritten font created for the Balsamiq Wireframes and has been in use since version 2.1.
The font contains 942 glyphs in 2 weights with italics/obliques, and includes the basic and extended latin character set, Cyrillic, Basic Symbols and Dingbats, Math and Technical Symbols, and punctuation
To contribute, see https://github.com/balsamiq/balsamiqsans