Blacktree Software is an American software company founded by Nicholas Jitkoff that specializes in freeware

Freeware

Freeware is computer software that is available for use at no cost or for an optional fee, but usually with one or more restricted usage rights. Freeware is in contrast to commercial software, which is typically sold for profit, but might be distributed for a business or commercial purpose in the...

 applications for Mac OS

Mac OS

Mac OS is a series of graphical user interface-based operating systems developed by Apple Inc. for their Macintosh line of computer systems. The Macintosh user experience is credited with popularizing the graphical user interface...

. Jitkoff is employed by Google

Google

Google Inc. is an American multinational public corporation invested in Internet search, cloud computing, and advertising technologies. Google hosts and develops a number of Internet-based services and products, and generates profit primarily from advertising through its AdWords program...

 and develops software for Blacktree in his free time.

Blacktree Software is best known for developing the now open source Quicksilver

Quicksilver (software)

Quicksilver is a computer utility software program for Mac OS X, originally developed by Blacktree Software and distributed freely. It is essentially a graphical shell for the Mac OS X operating system, allowing users to use the keyboard to rapidly perform tasks such as launching...

software, a unified, extensible interface for working with applications, contacts, music, and other data.