Connolly was born in 1967 and grew up with four siblings in Prairie Village, in the Kansas City metropolitan area, where he attended Bishop Miege High School.
[2] In October 1991, Connolly was working on the documentation tools team at Convex Computer when he joined the Web project's mailing list to discuss the browser he had written for the X Window System.
[3] He met Tim Berners-Lee and Robert Cailliau at the HyperText conference in San Antonio, TX, in December 1991.
Moving from Texas to Boston in 1994, he joined the newly created World Wide Web Consortium (W3C) at the Massachusetts Institute of Technology,[8] where Connolly took a position as research scientist at the Laboratory for Computer Science.
In June 2010, Dan left the W3C and took a position with University of Kansas School of Medicine as a Biomedical Informatics Software Engineer in their Department of Biostatistics.