Zawinski's programming career began at age 16 with Scott Fahlman's Spice Lisp project at Carnegie Mellon University.
Lucid decided to use GNU Emacs as the text editor for their IDE due to its free license, popularity, and extensibility, and Zawinski led that project.
[6] Zawinski came up with the name "Mozilla" (originally the internal code-name of the web browser) during a staff meeting, as a reference to Godzilla and a portmanteau of "Mosaic killer".
[9] Through his long-time support and advocacy for free software both inside and outside the company, Zawinski is credited with having been the inspiration for Netscape's decision to open-source the source code of the browser in 1998.
[10][11] He was a founder of Mozilla.org, personally registering its domain name on the day of Netscape's open source announcement and helping design and run the organization through its first year.
[18][19][20][21] Zawinski purchased the nightclub in 1999 for approximately 5 million dollars and it was re-opened in July 2001, a process which he documented extensively in a blog named "DNA Sequencing".
[29] He was also featured in Sleep Mode: The Art of the Screensaver,[30] a gallery exhibition curated by Rafaël Rozendaal at Rotterdam's Het Nieuwe Instituut in 2017.
In Peter Seibel's book Coders at Work: Reflections on the Craft of Programming, Zawinski calls C++ an "abomination... the PDP-11 assembler that thinks it's an object system".