Phil Katz and the Zip Format
Abstract
Every computer user knows the .zip file. Almost nobody knows Phil Katz, the Milwaukee programmer who created it, won the fiercest software fight of the BBS era, and then deliberately gave the format away by publishing its specification for anyone to implement. That decision made zip the universal container for compressed data and made Katz’s own product replaceable. He was found dead in a hotel room in April 2000, at 37, with an empty bottle of peppermint schnapps beside him.
Milwaukee and the Mailbox Scene
Phillip Walter Katz was born on November 3, 1962, in Milwaukee, Wisconsin, and grew up in suburban Glendale. He studied computer science engineering at the University of Wisconsin-Milwaukee and spent his nights where much of 1980s hobbyist computing lived: dialed into bulletin board systems (The BBS Era). On a 1200-baud modem, every kilobyte was waiting time and telephone charges, which made file compression the most practical software category there was.
The standard archiver of the mid-1980s was ARC, published by System Enhancement Associates (SEA). Katz found it slow, rewrote the compression routines in assembly language, and from 1985 released his versions, PKXARC and PKARC, as shareware on the boards. They were dramatically faster than the original and spread the way good shareware spread: sysop to sysop, board to board (Shareware and Public Domain). In 1986 he founded PKWARE, initially run from his home in Glendale, with family members helping manage the business.
The ARC War
SEA saw a competitor built on its own file format and, it claimed, its code. In 1988 it sued PKWARE for copyright and trademark infringement. The settlement of August 2, 1988, went SEA’s way on paper: PKWARE paid $22,500 in back royalties and $40,000 in costs, agreed to a 6.5% royalty on ARC-compatible revenue, and stopped developing ARC-compatible software.
The BBS community read the outcome differently. To the boards, SEA had lawyered a better programmer out of improving a de facto standard, and the reaction was a boycott in all but name. When Katz shipped a replacement, users recompressed their archives en masse, and some sysops refused .ARC uploads outright. SEA won the lawsuit and lost the platform; the ARC format was effectively dead within a couple of years.
PKZIP and the Open Format
The replacement was PKZIP, released in 1989: a DOS command-line archiver, shareware with a $25 registration fee, built on a new format of Katz’s own design so that SEA had no claim on it. With it came the decision that defines his legacy. Katz published the complete zip file format specification in a file called APPNOTE.TXT and declared that the format would remain free for competing software to implement, forever. Anyone could write a zip tool without paying PKWARE anything.
The format won on both merit and openness. PKZIP 2.04g (1993) introduced DEFLATE, Katz’s combination of LZ77 dictionary compression with Huffman coding, and DEFLATE escaped the zip file to become the engine of gzip, the PNG image format, and HTTP compression, arguably the most-used compression algorithm in history (Data Compression). The zip container itself ended up everywhere, from Java .jar files to Microsoft Office documents, which have been zip archives in disguise since 2007.
Openness cut the other way for PKWARE’s product. When computing moved to Windows, graphical tools like WinZip, built on the freely available specification, became what “zip” meant to ordinary users. Katz, a command-line purist, shipped a Windows version years late. The company stayed profitable; its founder had made his format immortal and his program optional.
The End
Katz’s success did not survive contact with his private life. His first alcohol-related arrest came in 1991, a drunk-driving conviction around 1992, then five more arrests through the 1990s for driving on a suspended license. He grew estranged from the family members who had helped run PKWARE and fired them in a dispute over access to the company’s profits. In his last years he was a millionaire with outstanding warrants, living out of hotel rooms and strip clubs while still holding the title of president of his company.
On April 14, 2000, Katz was found dead in a Milwaukee hotel room, holding an empty bottle of peppermint schnapps. The coroner recorded acute pancreatic bleeding caused by chronic alcoholism. He was 37. PKWARE passed to an investor group the following year and refocused on enterprise data security, where it still maintains APPNOTE.TXT, the specification Katz set free.