Capps started working at the Xerox Corporation while still a computer science student at the Rochester Institute of Technology. In 1981, Capps started working for Apple on the Lisa project and he continued his work on the Macintosh, principally writing the Finder (along with Bruce Horn) and Macintosh system utilities—such as ResEdit.
During a break in 1986, he wrote three music programs including Jam Session, SoundEdit, and Super Studio Session; SoundEdit was eventually sold to Macromedia. From 1987 to 1996, he was the chief architect and Apple Fellow for the Apple Newton, where he led the specification and development of the user interface of Newton, shepherded the team of software developers, and wrote many portions of the built-in application software. From 1996 until 2001, he was a user interface architect at Microsoft. His early work at Microsoft resulted in the Internet Explorer Search, History, and Favorites panes. He was also a co-founder of the MSN Explorer project.
As of 2010, he was working at Silicon Valley start-up Kwedit, now called PayNearMe, focusing on online payment systems. At that time he was married to lawyer Marie D'Amico and had one child, Emma T Capps, who was born in 1997.