For the first edition (2005)

This book took four times longer to write than I thought it would, and for much of that time felt rather like a grand piano suspended above my head wherever I went. Without help from many people, I would not have been able to complete it while staying sane.

Andy Oram, my editor at O'Reilly, was a writer's dream. Aside from knowing the field intimately (he suggested many of the topics), he has the rare gift of knowing what one meant to say and helping one find the right way to say it. It has been an honor to work with him. Thanks also to Chuck Toporek for steering this proposal to Andy right away.

Brian Fitzpatrick reviewed almost all of the material as I wrote it, which not only made the book better, but kept me writing when I wanted to be anywhere in the world but in front of the computer. Ben Collins-Sussman and Mike Pilato also checked up on progress, and were always happy to discuss — sometimes at length — whatever topic I was trying to cover that week. They also noticed when I slowed down, and gently nagged when necessary. Thanks, guys.

Biella Coleman was writing her dissertation at the same time I was writing this book. She knows what it means to sit down and write every day, and provided an inspiring example as well as a sympathetic ear. She also has a fascinating anthropologist's-eye view of the free software movement, giving both ideas and references that I was able use in the book. Alex Golub — another anthropologist with one foot in the free software world, and also finishing his dissertation at the same time — was exceptionally supportive early on, which helped a great deal.

Micah Anderson somehow never seemed too oppressed by his own writing gig, which was inspiring in a sick, envy-generating sort of way, but he was ever ready with friendship, conversation, and (on at least one occasion) technical support. Thanks, Micah!

Jon Trowbridge and Sander Striker gave both encouragement and concrete help — their broad experience in free software provided material I couldn't have gotten any other way.

Thanks to Greg Stein not only for friendship and well-timed encouragement, but for showing the Subversion project how important regular code review is in building a programming community. Thanks also to Brian Behlendorf, who tactfully drummed into our heads the importance of having discussions publicly; I hope that principle is reflected throughout this book.

Thanks to Benjamin "Mako" Hill and Seth Schoen, for various conversations about free software and its politics; to Zack Urlocker and Louis Suarez-Potts for taking time out of their busy schedules to be interviewed; to Shane on the Slashcode list for allowing his post to be quoted; and to Haggen So for his enormously helpful comparison of canned hosting sites.

Thanks to Alla Dekhtyar, Polina, and Sonya for their unflagging and patient encouragement. I'm very glad that I will no longer have to end (or rather, try unsuccessfully to end) our evenings early to go home and work on "The Book."

Thanks to Jack Repenning for friendship, conversation, and a stubborn refusal to ever accept an easy wrong analysis when a harder right one is available. I hope that some of his long experience with both software development and the software industry rubbed off on this book.

CollabNet was exceptionally generous in allowing me a flexible schedule to write, and didn't complain when it went on far longer than originally planned. I don't know all the intricacies of how management arrives at such decisions, but I suspect Sandhya Klute, and later Mahesh Murthy, had something to do with it — my thanks to them both.

The entire Subversion development team has been an inspiration for the past five years, and much of what is in this book I learned from working with them. I won't thank them all by name here, because there are too many, but I implore any reader who runs into a Subversion committer to immediately buy that committer the drink of their choice — I certainly plan to.

Many times I ranted to Rachel Scollon about the state of the book; she was always willing to listen, and somehow managed to make the problems seem smaller than before we talked. That helped a lot — thanks.

Thanks (again) to Noel Taylor, who must surely have wondered why I wanted to write another book given how much I complained the last time, but whose friendship and leadership of Golosá helped keep music and good fellowship in my life even in the busiest times. Thanks also to Matthew Dean and Dorothea Samtleben, friends and long-suffering musical partners, who were very understanding as my excuses for not practicing piled up. Megan Jennings was constantly supportive, and genuinely interested in the topic even though it was unfamiliar to her — a great tonic for an insecure writer. Thanks, pal!

I had four knowledgeable and diligent reviewers for this book: Yoav Shapira, Andrew Stellman, Davanum Srinivas, and Ben Hyde. If I had been able to incorporate all of their excellent suggestions, this would be a better book. As it was, time constraints forced me to pick and choose, but the improvements were still significant. Any errors that remain are entirely my own.

My parents, Frances and Henry, were wonderfully supportive as always, and as this book is less technical than the previous one, I hope they'll find it somewhat more readable.

Finally, I would like to thank the dedicatees, Karen Underhill and Jim Blandy. Karen's friendship and understanding have meant everything to me, not only during the writing of this book but for the last seven years. I simply would not have finished without her help. Likewise for Jim, a true friend and a hacker's hacker, who first taught me about free software, much as a bird might teach an airplane about flying.

For the second edition (2022)

The acknowledgements for the second edition of this book include more people and, undoubtedly, more unintentional omissions. If your name should be here but is not, please accept my apologies (and let me know, because we can at least fix the online copy).

Andy Oram of O'Reilly Media once again went above and beyond the call of duty as an editor. He read closely and made many excellent recommendations; his expertise both in expository writing in general and in open source in particular were apparent in all his comments. I can't thank him enough, and the book is much improved for his attention.

James Vasile has been my friend and colleague for well over a decade now, yet not a week goes in which I don't learn something new from him. Despite having a busy job — I know firsthand, because we're business partners — and young children at home, he unhesitatingly volunteered to read through the manuscript and provide feedback. Money can't buy that, and even if it could, I could never afford James. Thanks, pal.

Cecilia Donnelly is both a wonderful friend and was a supremely capable Open Source Specialist at the Open Tech Strategies office in Chicago. It's a delight to be working with her, as our clients know too, and her clear thinking and sharp observations have influenced many parts of this book.

Karen Sandler has been unfailingly supportive, and provided thoughtful and patient discussion about many of the topics (and even some of the specific examples) in this book. As with James, I usually learn something from Karen when we talk about free software, and when we talk about other things too.

Bradley Kuhn's name appears several times in the commit logs for this book, because he provided highly expert feedback on multiple occasions, in one case practically writing the patch himself. As I wrote in the log message for one of the commits, he is someone "whose contributions to free software have been immeasurable and whose dedication to our shared cause is a constant inspiration".

Karen and Bradley both work at the Software Freedom Conservancy ( If you like this book and you want to help free software, donating to the Conservancy is fine first step. It's also a fine second step.

Ben Reser provided a super-detailed and expert review of Chapters 6 and 7 that resulted in many improvements. Ben, thank you so much.

Michael Bernstein not only provided some detailed feedback during the interregnum between the first and second editions, he also helped a lot with organizing the Kickstarter campaign that made the latter possible. Thank you, Michael.

Danese Cooper always keeps me on my toes, and in particular brought me the message (which I was not at first willing to hear) that innersourcing can work as a means of helping organizations learn open source practices and eventually produce open source software themselves. Thanks for that, Danese, and much else.

Between the two editions, I spent a very educational stretch of time working at O'Reilly Media, Code for America / Civic Commons (while ensconsed in the Open Plans office in New York City, thanks to their very kind offer of desk space), and the New America Foundation as Open Internet Tools Project Fellow. Much of what I learned through that work ended up in the book, and in addition to the organizations themselves I thank Tim O'Reilly, Jen Pahlka, Andrew McLaughlin, Philip Ashlock, Abhi Nemani, Nick Grossman, Chris Holmes, Frank Hebbert, and Andrew Hoppin for the ideas and perspectives they shared.

Sumana Harihareswara and Leonard Richardson have given frank and helpful commentary about various open source goings-on over the years; the book is better for their input, and I am the better for their friendship.

Eben Moglen at the Software Freedom Law Center ( taught me a lot about how to look at free software as a large-scale social and economic phenomenon, and about how companies view free software. He also provided a private working space on a few occasions when it really made a difference. Thank you, Eben.

I do not understand how Dr. David A. Wheeler makes time to answer my occasional questions when he is in demand from so many other people as well, but he does, and his answers are always spot-on and authoritative. Thanks as always, David.

Breena Xie's interest in open source led swiftly to trenchant questions about it. Those questions were helpful to me, in thinking through certain topics in the book, but so was her patience on those occasions when the book demanded more time than it should have (by which I mean "than I said it would"). Thank you, Breena.

Many thanks to Radhir Kothuri and the rest of the HackIllinois 2017 crew, who provided a very timely motivational boost when they proposed doing a print run of the new edition for their event at the University of Illinois at Urbana-Champaign, Illinois in February 2017. I appreciate the vote of confidence in the book, and hope the HackIllinois attendees will be pleased with the results.

Camille Bégnis of provided expert DocBook help in real time one day, solving a long-standing technical problem in the online version of the book that I'd been unable to fix for years. Merci beaucoup, Camille.

My friend Jason A. Owen also provided timely and wonderfully thorough help with some DocBook formatting issues and with the build process, and is the reason it is now possible to generate PDFs of this book suitable for printing on different page sizes. Independently of that, Jason has been a valued collaborator on many open source projects, and raises standards wherever he's involved. Thank you, Jason.

The hardest part of these acknowledgements is realizing there will never be enough space to do justice to all the knowledge people have shared in the decade and a half since the first edition came out. I've been working in open source the whole time since then, and have had illuminating conversations with many clients, partners, interviewees, expert consultants, and fellow travelers; some of them have occasionally sent in concrete improvements to the book, too. I can't imagine what this new edition would be without the benefit of that collective mind, and will try to list some of those people below. I'm sure the list is incomplete, and I apologize for that. For what it's worth, I used a program to randomize the order, and accepted its first output:

Nithya Ruff, Jenn Brandel, Joseph Lorenzo Hall, Ben Wyss, Kit Plummer, Mark Atwood, Vivien Deparday, Sebastian Benthall, Martin Michlmayr, Derek Eder, Hyrum Wright, Stefano Zacchiroli, Dan Risacher, Stephen Walli, Simon Phipps, Francis Ghesquiere, Sanjay Patil, Tony Sebro, Matt Doar, Deb Nicholson, Jon Phillips, David Robinson, Nathan Toone, Alolita Sharma, Jim McGowan, Florian Effenberger, Brian Warner, Cathy Deng, Allison Randal, Ariel Núñez, Jeremy Allison, Thorsten Behrens, Deb Bryant, Holly St. Clair, Jeff Ubois, Dustin Mitchell, Dan Schultz, Luis Villa, Jon Scott, Dave Neary, Mike Milinkovich, Wolf Peuker, Paul Holland, Keith Casey, Christian Spanring, Bishwa Pandey, Scott Goodwin, Vivek Vaidya, David Eaves, Ed Sokolowski, Chris Aniszczyk, David Hemphill, Emma Jane Hogbin Westby, Ben Sheldon, Guy Martin, Michael Downey, Charles-H. Schulz, Vitorio Miliano, Paul Biondich, Richard Fontana, Philip Olson, Leslie Hawthorn, Harlan Yu, Gerard Braad, Daniel Shahaf, Matthew Turk, Mike Hostetler, Waldo Jaquith, Jeffrey Johnson, Eitan Adler, Mike Linksvayer, Smiljana Antonijevic, Brian Aker, Ben Balter, Conan Reis, Dave Crossland, Nicole Boone, Brandon Keepers, Leigh Honeywell, Tom "spot" Callaway, Andy Dearing, Scott Clark, Tina Coleman, William A Rowe Jr., Matthew McCullough, Stuart Gill, Robert Soden, Chris Tucker, Noel Hidalgo, Mark Galassi, Chris DiBona, Gerhard Poul, Christopher Whitaker, James Tauber, Justin Kestelyn, Nadia Eghbal, Mel Chua, Tony Wasserman, Robert Douglass, Simone Dalmasso, John O'Nolan, Tom Marble, Patrick Masson, Arfon Smith, Forest Gregg, and Molly de Blanc.

The 2nd edition rewrite was funded through a Kickstarter campaign. The response to that campaign was swift and generous, and I'm immensely grateful to all the people who pledged. I hope they will forgive me for taking almost four times longer than expected to finish the revisions. Every backer of the campaign is acknowledged below, using the name they provided via Kickstarter. The list is in either ascending or descending order by pledge size, but I'm not going to say which, because a little mystery should be retained in these matters:

Pablo, Cameron Colby Thomson, Bethany Sumner, Michael Lefevre, Maxim Novak, Adrian Smith, Jonathan Corwin, Laurie Voss, James Williams, Chris Knadler, Zael, Kieran Mathieson, Teresa Gonczy, Poramate Minsiri, j. faceless user, Michael, Isaac Davis aka Hedron A. Davis, James Dearing, Kyle Simpson, Laura Dragan, Hilary Mason, Tom Smith, Michael Massie, Erin Marchak, Micke Nordin, Xavier Antoviaque, Michael Dudley, Raisa, Paul Booker, Jack Moffitt, Aaron Shaw, maurine stenwick, Ivan Habunek, G. Carter Stokum, Barry Solow, mooware, Harish Pillay, Jim Randall, Holger S., Alan Joseph Williams, Erik Michaels-Ober, David Parker, Nick, Niko Felger, Fred Trotter, Dorai Thodla, William Theaker, Hans Bakker, Brad, Bastien Guerry, Miles Fidelman, Grant Landram, Michael Rogers, mostsignificantbit, Olivier Berger, Fernando Masanori Ashikaga, Naomi Goldenson, Brian Fitzpatrick, Eric Burns, Mark V. Albert, micah altman, Richard Valencia, Cody Bartlett Heisinger, Nick Grossman, cgoldberg, Mike Linksvayer, Simon Phipps, Yoshinari Takaoka, Christian Spanring, Ross M Karchner, Martin Karlsson, Kaia Dekker, Nóirín Plunkett, Emma Jane, Helior Colorado, Fred Benenson, George V. Reilly, Lydia Pintscher, Noel Hidalgo, Albert White, Keng Susumpow, Mattias Wingstedt, Chris Cornutt, Zak Greant, Jessy Kate Schingler, James Duncan Davidson, Chris DiBona, Daniel Latorre, Jeremiah Lee Cohick, Jannis Leidel, Chris Streeter, Leonard Richardson, Terry Suitor, Trevor Bramble, Bertrand Delacretaz, John Sykora, Bill Kendrick, Emmanuel Seyman, Paolo Mottadelli, Gabriel Burt, Adrian Warman, Steve Lee, Andrew Nacin, Chris Ballance, Ben Karel, Lance Pollard, richardj, Brian Land, Jonathan Markow, Kat Walsh, Jason Orendorff, Jim Garrison, Jared Smith, Sander van der Waal, Karen Sandler, Matt Lee, John Morton, Frank Warmerdam, Michael R. Bernstein, John Yuda, Jack Repenning, Jonathan Sick, Naser Sharifi, Cornelius Schumacher, Yao-Ting Wu, Camille Acey, Greg Grossmeier, Zooko Wilcox-O'Hearn, Joe, Anne Gentle, Mark Jaquith, Ted Gould, James Schumann, Falkvinge, Schuyler Erle, Gordon Fyodor Lyon, Tony Meyer, Salvador Torres, Dustin J. Mitchell, Lindy Klein, Dave Stanton, Floyd DCosta, Agog Labs, Adrià Mercader, KIMURA Wataru, Paul Cooper, alexML, Stefan Heinz, maiki, BjornW, Matt Soar, Mick Thompson, mfks, Sebastian Bergmann, Michael Haggerty, Stefan Eggers, Veronica Vergara, Bradley Kuhn, Justin Tallant, dietrich ayala, Nat Torkington, David Jeanmonod, Randy Metcalfe, Daniel Kahn Gillmor, George Chamales, Erik Möller, Tim Schumacher, Koichi Kimura, Vanessa Hurst, Daniel Shahaf, Stefan Sperling, Gunnar Hellekson, Denver Gingerich, Iliana Weller, adam820, Garance Drosehn, Philip Olson, Matt Doar, Brian Jepson, J Aaron Farr, Mike Nosal, Kevin Hall, Eric Sinclair, Alex Rudnick, Jim Brucker, PEI-HAN LEE, Michael Novak, Anthony Ferrara, Dan Scott, Russell Nelson, Frank Wiles, Alex Gaynor, Julian Krause, termie, Joel McGrady, Christian Fletcher Smith, Mel Chua, William Goff, Tom Liesenfeld, Roland Tanglao, Ross Gardler, Gervase Markham, Ingo Renner, Rochelle Lodder, Charles Adler, Dave Hylands, Daryn Nakhuda, Francois Marier, Kendric Evans, Greg Price, Carlos Martín Nieto, Greg Stein, Glen Ivey, Jason Ray, Ben Ubois, Landon Jones, Jason Sperber, Brian Ford, Todd Nienkerk, Keith Casey, Leigh Honeywell, Aaron Jorbin, Christoph Hochstrasser, Miguel Ponce de Leon, Dave Neary, Eric Lawrence, Dirk Haun, Brian Burg, Brandon Kraft, Praveen Sinha, ML Cohen, Christie Koehler, Ethan Jucovy, Lawrence S Kemp, Justin Sheehy, Jonathan Polirer, Ronan Barzic, Greg Dunlap, Darcy Casselman, Jeremy G Kahn, Sam Moffatt, James Vasile, Simon Fondrie-Teitler, Mario Peshev, Alison Foxall, Jim Blandy, Brandon Satrom, Viktor Ekmark, Tor Helmer, Jeff Ubois, Gabriela Rodriguez, James Tait, Michael Parker, Stacy Uden, Peter Martin, Amy Stephen, James Tauber, Cameron Goodale, Jessica, Ben Sheldon, Forest Gregg, Ken McAuliffe, Marta Rybczynska, Sean Taylor, John Genego, Meeuw, Mark MacLennan, Kennis Koldewyn, Igor Galić, Henrik Dahlström, Jorren Schauwaert, Masahiro Takagi, Ben Collins-Sussman, Decklin Foster, Étienne Savard, Fabio Kon, Ole-Morten Duesund, Michael Downey, Jacob Kaplan-Moss, Nicola Jordan, Ian Sullivan, Roger W Turner, Justin Erenkrantz, Isaac Christoffersen, Deborah Bryant, Christopher Manning, Luis Villa, Judicaël Courant, Leslie Hawthorn, Mark R. Hinkle, Danese Cooper, Michael Tiemann, Robert M. Lefkowitz, Todd Larsen, T Foote, Ben Reser, Dave Camp, Scott Berkun, Garrett Rooney, Dinyar Rabady, Damien Wyart, Seth Schoen, Rob Brackett, Aisha, Winnie Fung, Donald A. Lobo, Dan Robles, Django Software Foundation, Mark Atwood, Krux Digital, Stephen Walli, Dave Crossland, Tina, and Thorsten Behrens.

Thank you all.