[1][2][3] Walden started his career working as a programmer at the space communications division of Massachusetts Institute of Technology's Lincoln Laboratory.

It was here that he was part of the seven-member engineering team that developed the packet switching technology that powered the ARPANET, one of the first general purpose computer networks that was a precursor of the modern internet.

[4] Specifically, Walden's efforts focused on developing the packet switching and routing software for the IMP.

[3] He was also a member of the TeX Users Group and contributed to content related to digital typesetting and publishing.

[13] Walden received a honorary doctorate from the San Francisco State University in 2014, for his contributions to the ARPANET.