This discussion took place during the Stack Exchange 1.0 days, when FogCreek sold Stack Exchange licenses for a fee.

It is worth noting that Stack Exchange licenses are still being sold for intranet use.

Important Caveattm: this is something we are merely discussing that may happen more than one year from now, if it happens at all. Bearing that IMPORTANT CAVEAT in mind, please read on.

Joel is convinced that open-sourcing Stack Overflow, in any way, shape, or form, will destroy the business model of StackExchange (pushing prices down to hosting commodity levels) and possibly the Stack Overflow family of sites as well (fragmentation & dissipation of audience via army of clone sites).

  1. Does open sourcing Stack Overflow even make sense at all? What do we (stackoverflow.com llc) get out of it? What does the community get out of it? Is it "win-win"? Or does someone lose?

  2. Are there "hybrid" models of open sourcing that could work? Rather than treating this as an "all or nothing" scenario, is there a way to open source parts of what we're doing, or restrict licensing so that we don't compete with ourselves in the hosted StackExchange part of the business?

  3. Aren't there other companies pursuing open source and hosting businesses at the same time? Such as Six Apart and Movable Type? I'm not sure how applicable this is to hosting business models, but certainly Slashdot and Reddit have gone open source. DotNetNuke also runs a similar business model, apparently.

  4. Won't we be competing with open source versions of ourselves anyway in the long term? There are certainly already open source Stack Overflow clones, and lots of open source FogBugz competition and clones. Over time, won't the competitive pressure increase from the continual improvement of open source copies of what we do? Would it make sense to do it ourselves so we control it?

  5. Could there be "enterprisey" closed source and "public" open source parts of the business? I've always said that StackExchange is going to have to fork because their private small, medium, and large business audience will want very different things than the public internet audience we serve. Wouldn't this be one way to segment the "free as in whatever the heck it is we're calling free these days" open-source dev work from the value-add closed source product?

Thoughts? Feelings? ... ponies?

  • 4
    Sort of reminds me of KnowledgeTree (knowledgetree.com), which they open sourced the code but kept all the enterprise-y stuff under closed sourced and only available in their commercial editions. Having used their OSS version for close to 3 years and seeing them thriving, probably it's worth looking to see how they had packaged their deals. Commented Jul 7, 2009 at 10:57
  • 7
    Just keep in mind that cloning SO is so easy. Probably a month of work. As we all know, cloning is much easier than building the thing in the first place.
    – mmx
    Commented Jul 7, 2009 at 11:38
  • 42
    i'd say 6-8 weeks...
    – geocoin
    Commented Jul 7, 2009 at 14:45
  • 2
    @Merdad: There is a clone of the engine underway, as I recall. I believe they've been working on it for over a month (at least) and they are still quite always behind. Fact is, Jeff and Joel have set a standard with these sites.
    – Frank V
    Commented Jul 7, 2009 at 18:13
  • 1
    Really, please don't open source it. Tons of clone sites will suddenly appear. Domain snatchers will get "staackoverflow.com" and use the open source engine to make a little fake stack overflow loaded with ads. Please no!
    – deleted
    Commented Jul 10, 2009 at 3:54
  • 7
    Like you mentioned in a blog post, tons developers on this site could clone it in a weekend if they wanted. Like you mentioned the level of polish SO has would be hard to achieve in a weekend, but making it open source will lead to blatant copies and bad implementations that would deface the reputation for excellence SO has. Maybe what you could do to give back to the community is have a weekly/monthly blog post that details techniques you use and goes over code. Blog posts like this would in a nerdy way be really exciting. I know I would be looking foreward to it each week.
    – teh_noob
    Commented Jul 11, 2009 at 23:51
  • curious what kind of license you would Open Source SO - BSD? GPL? CPAL?
    – user132619
    Commented Jul 31, 2009 at 19:04
  • 7
    @teh_noob: "Maybe what you could do to give back to the community..." IMO, StackOverflow (and friends) is already a valuable gift to the community.
    – P Daddy
    Commented Sep 4, 2009 at 1:19
  • @Jeff, Joel, et al.: I doubt the unobtrusive ads on these sites generate huge income (relative to the traffic). I hope you sell StackExchange like gang busters. If you open source it, you're selling what? Hosting? For $129/month and up?
    – P Daddy
    Commented Sep 4, 2009 at 1:23
  • This isn't worth adding a new answer so I'll do it in the comments. But I think you should become more esablished on the internet before open sourcing yourselves. And when you do make it hard for the newbies to rip you off. Commented Jan 6, 2010 at 14:24

65 Answers 65


You have a large range of options when it comes to open sourcing. Whether you choose, say, a GPL license or a BSD license will have a large impact on what people can do, as I'm sure you're well aware.

I'd say the safest model to choose is a dual-licensed model where code can be used for free under a viral license (eg GPL) but can be licensed commercially too. In some ways this is the best of both worlds but it does have a downside.

The real benefit of open source is that you get developer involvement essentially for free (apart from the time required for someone to organize and lead the project). The negative of the dual-license model is that if people contribute code under say the GPL license, you will have a tough sell convincing them to let you sell it commercially too.

The plus side of any open sourcing of course is that you will get free development done.

Personally I wouldn't worry about the impact of competing with IllegalArgument.com. You were here first and will have a large loyalty base as a result (like Digg and Reddit). Ultimately, it's not hard to duplicate the functionality of StackOverflow once you've seen it. I know theres nothing here I couldn't write and I think we're talking only man-months to produce something with most if not all of the functionality. By open sourcing, you can probably head off such efforts and then control the licensing as people will more likely use yours than duplicate it.

The downside of any open source effort as well is that once you've done it you can't take it back.

Other potential models including providing the source code for free but charging for support. I don't know if this would suit SO but it works for MySQL and others. JasperReports does this too and they have a dual license model but don't accept contributions to the official source because of the aforementioned issues.

In doing this you could also provide a basic version for free and have a better commercial version either by way of:

  • Modularized behaviour, although other people can always duplicate this;
  • Indemnity;
  • Putting limits on the free version such as non-commercial use or limit the number of users, posts or some other such limitation. Personally I'm not a fan of the "crippleware" approach however.

Thing is, the SO code really isn't all that valuable. It wouldn't take long for a few good people to have a half-assed duplicate ready to go, and then polish it. Three full-time people cannot keep far ahead of an interested community. In a year, we'd likely have Gnu Overrun, no matter what.

This means that there will be OS SO clones out there, if there is interest. There's nothing you folks can do about that. The current SO people can keep all the trademarks, and those will be worth something, at least as long as they stay on top.

Therefore, open-sourcing SO will not lose much, if any, revenue. It will be a case of the trademarked SO vs. a non-trademarked (or at least with less valuable trademarks) OS version, no matter whether SO is open source or not. Either the trademarks will carry the original SO or they won't, and the code really doesn't matter. The market will drive towards commodity hosting prices, no matter what. There will be companies who are willing to pay premium prices for the real SO from StackExchange, but they will do so regardless of whether SO is open source or not, and they will expect premium service.

There's also a question of what open sourcing SO would gain you people. You'd have some development assistance, although I don't know how valuable that would be. You'd generally find and identify bugs earlier.

It may or may not contribute to the community spirit. What makes SO a success is the community, not the software. Having the software OS might make people feel like more of a community, and might attract more Open Source and Free Software people, which would be good.

So, frankly, it isn't going to make much difference. There will be OS/Free Software setups that do pretty much the same thing, no matter what. The hosting prices will be driven towards commodity hosting prices, no matter what. The real thing will command something of a premium price (although probably not the projected rates) no matter what.

Given that, I'd recommend OSing SO, and hoping it will help the SO community.


I can see a good combination of two approaches:

Dual-licensing with AGPL and a proprietary license: It's the model Qt has taken and it seems to have worked quite well for them. Few competitors would give back code, so you get paid by them while letting the community have its share;

Hosting with paid advanced features: Wordpress.com charges for the simplest things (like editing CSS), even those that are available on the open-source version. You could offer similar free hosting, with your own ads, while charging for:

  • customizing CSS
  • having one's own domain
  • advanced moderation features
  • hosting one's own ads (maybe a rev-share model?)
  • database dumps
  • extra storage space
  • speed (privileged hosting)

The reason not to open source would be because you would gain less revenue. (which isn't the same as losing revenue: hardly anyone who downloads Photoshop would pay for it if they couldn't download it, so it's not revenue lost)

Would you gain less? StackExchange might gain less revenue, but StackOverflow wouldn't.

The on the other side, the only reason I can see to open-source it is to get it more widely used than a service like StackExchange can make it, or to head off competitors that are doing similar.

In other words, the reason is because it would be free-like-beer. The fact that it would be free-like-speech wouldn't give many benefits at all: The product works well so there's not a huge amount of development work you need to do that can't be done in-house. And any work done externally would have to be vetted in-house anyway, so you'll need to pay that guy.

If you did decide you wanted to go the Open Source route, follow the MySQL or RedHat path: it's all open source, but support is provided at a cost. That means you will sell it to the enterprise crowd who need solid support contracts before they can begin to look at a product. You can sell it (via StackExchange) to the crowd who have no idea (and don't want any idea) how to set it up for themselves.

Sure, there will be other people who will compete with StackExchange using your product. But that's going to happen anyway, just using some other open-source initialtive that works the same way.

(Note that this yet-to-be-discovered competitor will be writing it in PHP or Ruby or Python -- all languages that have huge Open Source followings. ASP.Net just isn't that big for open source because it's based on closed-source libraries and compilers. This means that you'd be losing the competition for people to help you write it, so again the argument is all about free-like-beer.)


Aside from releasing source the alternative would be to license SO. I would push for a purchase in my org.

It is a great way to organically build a knowledge base over time, and I think that piece is missing in a lot of places - especially stovepipe orgs. Given the competitive nature of the badge system it would encourage average employees to contribute their knowledge for recognition - which would help break down information barriers. It would also allow you to identify who in the organization knows about what, and which people are holding the place together.

As a programmer if I could go to a LAN instance of SO about... say accounting, ask an accounting question, and get answers from people in 4 divisions, that would be awesome.


I am sure that you aren't the first to comtemplate / go down this road. What has the experience of others been as a result of going open source (in some way shape or form) and what were their motivations in doing this in the first place? I think for some it has been desperation, for others a shrewd move since it has enabled others to build plugins for a solution.There are other companies like sugar crm taking an approach see here http://www.sugarcrm.com/crm/community/sugarcrm-community.html .

The approach you are taking with stack exchange is an interesting one in that at one level you are a business which operates consumer sites and in another you are then looking to commercialize the same back end software for end users. So as far as I can see for $1,299 a month i could setup a competitor to stackoverflow with yourselves - and you are worrying about open sourcing it and generating a competitor? $15,000 a year isn't a lot of money to setup a competitor! Thus this leads me to the question - where do yourselves see the revenue opportunities for stack overflow? I think if you answer this question then whether, if and in what form you go open source will come out in the wash.

I suspect quite a few people would be interested in just looking at the source since yourselves were early in on the ASP.NET MVC scene.

Trust this helps.


Not only will open-sourcing stack overflow hit your business model, but also mere talk of it will hurt the business model.

So I think you just decide pretty soon and announce you will never open-source stack overflow.

Having said that, Jeff, you have my email and I would be glad if in exchange for this suggestion you sent me the latest tarball with installation instructions so that I can tinker with Stack Overflow.


Turn the question on its head: How does freeing (not to be confused with open-source which misses the point) change the game for stackoverflow.com LLC?

There is only one reason to free your software: enable your users, provide them with the freedom that comes with your software, the freedom to implement all of those UserVoice features and bug fixes they've been whining about.

Fact is, with the correct license (e.g. Affero GPL as suggested above), your competition will only come from companies and individuals that share your views (and goals) of free software. Any competitor will have to do the same thing as you: create value for the end-user. I dare say, nobody does this better than you and therefore you have nothing to fear from freeing stackoverflow.

  • You link to an article about open source / free software that is only available as premium content? Oh, the irony. Commented Jul 8, 2009 at 0:36
  • 1
    Come on man, it's Stallman. Do you really think he would tolerate that? Try gnu.org/philosophy/open-source-misses-the-point.html.
    – Anonymous
    Commented Jul 9, 2009 at 23:12

Jeff, consider this:

When it comes to the actual content of the site, Joel seems to embrace the bazaar model. He wants the silly questions and the big, involved questions too. From some things you have said on the podcast, I get the impression that you would like to keep the content as refined as possible and at times you actually seem annoyed by questions you deem to be beneath the site.

What do you think it's going to be like when people who you don't agree with are changing the code base as well as the content in a way you do not like?

  • 1
    Who says everybody gets to change the code base? They'd be free to fork off their own version, but they'd have to build their own community. Commented Jul 7, 2009 at 21:45
  • true, but they'd fork Commented Jul 8, 2009 at 11:54

Several have suggested that the main value of open-sourcing is the "free" programming work. However, the success of the SO framework, imho, is it's simplicity. We all know it works well... right now. Yes, there are lots of tiny burrs that could be polished off, but the core is already successful.

Having said that, I think that the core question to resolve is whether there will be successful alternative open-source competitors (question 4). I think that this is inevitable, and "owning" the SO framework that everyone uses for this type of site might be more valuable than eeking out the profits from SE for a half-dozen years.


A popular reason to open source Stack Overflow would be so that people who want to host it for free (say, people running non-profits or open source projects) can host an instance.

Why not have a version of StackExchange available to non-profits and open source projects for free, thus negating the need for those people to use a clone?

  • Turn that around - why go the trouble and risk of releasing the code if there will be clones for those customers anyway? Commented Jul 10, 2009 at 2:57
  • 1
    non-profits might use a free-but-closed-source SE, but open-source projects would never allow themselves to depend on anything that wasn't open-source. for most free software types (including me), Freedom/Open-Source is an attribute that rates far higher than most or even all other attributes. they'd choose a free clone instead, even if it was clearly inferior. note: this is not a comment on whether SE should or should not be open-sourced, just about FOSS culture software preferences.
    – cas
    Commented Jul 13, 2009 at 9:28
  • Your "open source projects would never allow themselves to depend on anything" doesn't count Launchpad, or all the Confluence/JIRA installs. OSS people can be pragmatic too. Why are open source programmers answering Qs on SO if the platform isn't OSS? Freedom of the data is as important, if not more, than freedom of the platform.
    – crb
    Commented Jul 14, 2009 at 12:23
  • Joel said on the podcast that he will let non-profits have it at no charge. I haven't heard him say the same for open source projects.
    – raven
    Commented Jul 17, 2009 at 20:23

Why not a hybrid model? Open Source for people that won't pay anyway, like non-commercial entities, open source projects, etc, and only make enterprises pay with a clause in the open source licence that explicitly disallows commercial use.

You will get the best advantages from both worlds.

  • 4
    a license that explicitly disallows commercial use is NOT an open source license. access to source code is only part of the FOSS philosophy. The major part is the freedom to do whatever you want with the code, without restriction (typically the only restriction that FOSS types accept is that you can't redistribute it with more restrictions than were in the original license - e.g. GPL copyleft style licenses - and even that's not universally accepted - e.g. BSD style licenses)
    – cas
    Commented Jul 13, 2009 at 9:33
  • Who cares about terminology and what FSF thinks is Open Source or not. Available code == open source for me.
    – Terminus
    Commented Jul 13, 2009 at 17:48
  • 4
    yes, you're right. pedantic concern over terminology is so silly. i really want to believe that when i get my electricity bill, when they say "payment is due by DATE", they're actually promising to give me that money by that date. that's my definition, and i'm sticking to it.
    – cas
    Commented Jul 13, 2009 at 22:36

It should be mentioned that open source and free software are slightly different concepts, but I'll use them here interchangably anyway, with the meaning of free software.

1) There are many ways in which you can consider whether open sourcing makes sense. Gains/losses are one significant angle. There is also a philosophical one.

In the philosophical sense, freeing the code is itself a goal - the rationale being the same that science tires to embrace: advancing the body of human knowledge, or in this case the codebase of humanity. Things to consider here is not what gains will be gotten from making the software free, but rather what will losses will be made (if any), and whether they can be afforded. In this view, closed source is a bit like hiding a cure for common cold and selling it for rich people - somewhat shady business, but it happens.

From the utilitarian gains/losses angle, you need to consider the affected parties, as you already stated in the question. What do you gain/lose? What does the community as a whole gain/lose? What do other individuals gain/lose?


  • You gain improvements to the code by the community - not just new stuff being coded, but also multitude of eyeballs checking the code for errors. Usually, this is an overstated advantage, but considering your audience has a lot of skilled coders, it might be very significant.
  • Also if you release with AGPL, you may even gain improvements from competing business, as they'd have to release their modifications. Whether this is significant, it's hard to tell.
  • Also from utilitarian view, you gain karma points - a lot of people seem to like open source, and freeing you code would make a great impression to the open source community.
  • The community gains the possibility to improve on your code, whether directly through submissions to your code, or by forking to develop for other purposes.
  • The community gains other problem-solving sites with quality code - as people, inspiried by the awesome code of SO, start setting them up for all kinds of topics.
  • This also means an important gain: Other individuals gain the possibility to set up their own sites - even for non-profit or private scenarios. Not everyone has money for StackExchange. Then again, there already are open source alternatives.


  • You may lose some business of StackExchange, but I don't feel confident in guessing whether this will happen and how much you lose. In any case, it's doubtful that you gain business.
  • The community may lose coherency and quality of problem-solving sites. If multiple copies spring up, it might dilute the problem-solving field and reduce quality as the other sites probably wouldn't be as well maintained. I don't expect the community for programming questions to disperse from here, but for other topics this may be a problem.
  • The community may lose your contribution - if there's no StackExchange business model, and everyone and their friends are hosting problem-solving sites, are you anymore interested in improving this system rather than just letting the community deal with it?
  • Other individuals can't really lose anything, since they're only given stuff.

4) You will indeed inevitably be competing with open-source options. If you go open source, you'll probably be controlling the progress. You can delay this until the open source alternatives are starting to gaining community and popularity - but if you delay too much, you'll need to work a lot to get to the top, since everyone will be focused on the alternative that was open source from the beginning.

The relevant question here is, does it matter whether you are in control or not? You'll always have SO code for your sites, regardless. The risk for you is that an open source alternative becomes a lot better, and people start migrating there, so you have to work to keep up with the competition. You could avoid the work by going open and just controlling the progress yourselves. Then again, I don't expect OS alternatives to get attractive enough for migration in a long time, but who knows.


Open-sourcing is good. Open-sourcing Stack Overflow is a bad idea. It's so close to a finished product already. One of the major reason to open source a project like this (that I can see) would be to make it work on more platforms and that works directly against your business model, which is to monopolize on the Stack Overflow engine.

One thing I see lacking from your business model is the freebie choice. 10 clicks, no cost and you've got your own mini-Stack Overflow. Sounds bad for business? On the contrary, because this mini-Stack Overflow will be limited enough so that only the people who would never consider paying any big amount for the Stack Overflow engine will keep on using it. The most recent site using this business model that I can think of is Google App Engine (You may say that it is open source, but that's just the framework; not the stuff behind that makes it all tick. Not to mention the hardware requirement it has.)


If you're not going to open source it, then you might create some lower priced tiers for freelancer/small business.


You probably already know it but there is a Spanish social news site called Meneame ([meneame.net]) which platform was open-sourced from the beginning and they are still getting about 80k daily unique visitors (Google trends said: http://trends.google.com/websites?q=meneame.net%2C+stackoverflow.com&geo=all&date=all&sort=0 )

It's true that they didn't built it thinking about business models but they are making some money with it.

And of course they got a lot of clones, but they are the reference and the community was already built that's what makes Meneame to have an added value.


As a business model, you generally want to commoditize your complements ... not your own business.

For a for-profit business, open sourcing software makes sense if it drives sales of something else. What would releasing the SO engine as open-sources achieve from a business standpoint?

  • Community contribution of development time? Possibly, but much of the cost of releasing software comes from testing and maintenance - not necessarily development.
  • Having the community find and fix bugs? Can't see that for SO, it seems to be stable and the types of defects that are out there don't drive people away from using the site.
  • Increased market visibility / marketing benefits? Possibly, since I suspect that sales of SO hosting will be driven more by word of mouth than advertising. However, having poorly managed clone sites could just as easily discourage customers - if they're bad enough.

Personally, I think it's hard to make a compelling business case for open sourcing something like SO - and I have yet to hear one.


Don't fix something that works.

You can always open-source it later if it makes sense, the opposite is impossible.

  • Exactly, this question is asking if it makes sense now. Commented Jul 8, 2009 at 17:24

My perspective is that you only gain goodwill.

You do not gain in perceivable quality, you do not gain in security, you do not gain in features.

You lose time in reviewing submitted patches, you lose corporate marketshare from forks, and you lose potential community members due to fragmentation of the market.

However, I would suggest - tentatively - that you may want to partner with a Big Iron-y company to see what their needs are for this kind of software. Perhaps that company would get a special rate, in exchange for being a "Friends and Family" contributor to SE features/licensing model.

I do not believe that offering something for nothing(open source) is a viable business model. I do not see how it fits into a functional and viable theory of real-world economic behavior.

  • Not just big-iron: talk to hosting companies to be resellers. They buy licences to run their own StackExchanges based on the number of _______ (registered user on each site | per site | flat fee ) Commented Oct 4, 2009 at 5:05

One alternative to providing an open-source version would be to provide a Free version on StackExchange, similar to the way that UserVoice does it. The reason that people would want an open-source version would be to run it for their site, for free. If you provide that functionality for them, there would be much less need for it (other than making changes to the code/functionality).

One reason that it WOULD benefit the community would be to show off the quality of the code. This is a programmer's haven. I'm sure that a lot of people here would LOVE to see the code, just to use it as an example of a great codebase. Perhaps a license like the Microsoft .NET source code license would apply (look but don't touch).


Open Sourcing SO is a horrible, horrible idea. Please do not do it.

As someone who plans to launch half a dozen SO sites as soon as I can, I want to pay you money. Please let me do that.

  • 1
    In the name of all that is holy: why wouldn't you be able to pay these guys money if it was open source???? Commented Sep 28, 2010 at 8:19

Digium has managed to open source their asterisk software while maintaining an Enterprise version. Redhat (RHEL vs Fedora || CentOS) and Novell (SLED vs OpenSUSE) have done the same too ...

I would like to see an open source version of StackExchange - I would love to start a site for car enthusiasts - oilchange.org or something similar - but I can't really justify investing the money for the StackExchange service.

Really, it depends on the Open Source License you choose, you write your own license that prevents people using the software, or any derivative of it, in a manner that competes with you, but allows them to use it freely for their own purposes - ie: a company can't start their own hosted StackExchange service, but they can create a site for hobby-electronics or something ...


Slightly off topic though already sort of mentioned. What about a free closed source version of Stack Overflow for download?

I'm thinking along the lines of things similar to Microsoft's 'Express' editions of Visual Studio where the product works but has certain limitations built in.

You could for example create a free to download but closed source 'Stack Overflow Express'. It could be limited by for example, only working with SQL Server express (total database size 2GB Max), no support for running ads, limited number of page views a day, limted number of total users, limited styling support, no plugins, etc etc.

This would make a great free product for interanet or extranet use within small companies, organisations or groups and not impact on the business of getting the big users to buy the real thing.


From a purely selfish standpoint, I would love to see the source, as it is clear that the site has been done "correctly" in so many different ways, and I think it would make me a better developer.

If you did open-source it, you would have to license it in a way that protects you from direct competition, as I honestly think you guys should be the only ones in this space. Having two or more StackOverflows on the internet would only dilute the model.

I also think you should be very choosy about who gets write access to the code repository. These people would have to be totally dedicated to the purity of the Stack Overflow concept, and the only way to be sure of that is to retain complete control.

Undoubtedly you would face competitive pressures from clones who use your code. But your secret sauce is not the code itself, it's the social model you have constructed that is embodied by the code, and that has already been open-sourced.

I wish I had a crystal ball and could tell you what the best business model is. Nowadays its seems that the more you give away, the more exposure you get and (potentially) the more revenue you can capture. But I think you already have your audience. From a business standpoint, I don't see how open-sourcing StackOverflow will help you.

  • If you limit what people can do with the code, it's not open source. As per talks on the podcast, the direct competition with SO is not a problem as SO has the momentum. Questioners and Answerers go there already. If you offered the same community the same service on a differnt domain name, they're just not going to move. Commented Oct 4, 2009 at 5:01

I humbly suggest that the value of making this project open source may come from the following scenarios:

  1. The perception that there will be code review by the public will encourage higher quality code production (this may not be the case, but it is a motivator). This is an often overlooked and highly valuable consideration in many closed-source development scenarios.

  2. Actual review by the public has the potential to reveal security issues, and more importantly the turnaround from the community for a fix is typically overnight.

  3. Free porting to other platforms increases the size of the potential marketplace for support contracts.

  4. Open sourcing the project allays concerns about lock-in, or that the product not remain available into the future (who knows, a law in Utah may someday prohibit the StackExchange SAAS model...).

  5. Peddling (slightly difficult) open source software creates revenue models for support.

  6. Open sourcing the project will allow others to turn it into something newer and better, and in particular further the ability to integrate with other software projects.

  7. Open sourcing the project will destroy the motivation for an open source equivalent to arise in competition to your own project.

Measuring these against your project is a non-trivial problem! Best of luck.

  • 1
    I'd argue that 1, 2 and 3 won't be as good as you think: it's written in ASP.NET or some similar MS language. The community of open-source developers is small, so you're more likely to have the cracker community finding exploits than the developer community doing code review. Same problem for porting: you can easily port open languages, but porting something written in ASP.NET will be horrendously difficult that the port is really just a competitor Open Source product written in Perl/PHP/Python/Ruby. #7 is likely if it's closed source, but as per above, just as likely if it's open source. Commented Oct 4, 2009 at 4:58
  • #7 makes no sense to me - there are LOADS of "duplicate" oss projects out there
    – warren
    Commented Oct 26, 2009 at 8:41
  • 1
    @Warren: Exactly the point. There are loads of duplicate oss projects out there. If Stack Exchange was open source, that would not be the case. Commented Oct 27, 2009 at 2:43

Haven't read all 50+ answers, but here are my opinions:

  1. Open-source the concept only. There are still Java, Ruby, etc. developers out there, who don't C#

  2. Not much, as you would decline almost everything.

  3. Don't know.

  4. No, just keep the quality bar high and use modern scientific methods to optimize the community's behavior.

  5. If you want to sell the engine, no problem there.

Btw, how do you imagine a business version of SO? A corporate knowledge base or something?

If I were you, and I was low on money, I would ask for donations, and perhaps ask god to help me out some way. Or any minor gods out there.


I have one word for you: data

The actual codebase for stack overflow is not that important, what has value is the questions. So I reccomend that you wait until stack overflow has so many questions any clone would be useless due to lack of questions. By that point even moving all the questions over would be useless, because people will go and look on stackoverflow.com and not some random clone.

Due to the reasons mentioned above your business model is not at risk relying you don't mistreat your community.

  • ?? the CC data dumps could be imported into a clone
    – warren
    Commented Oct 26, 2009 at 8:45

Make your money by offering hosting and customization. If you get some big customers, they are going to want customized changes that go beyond CSS. They will expect AD integration. They will want attachments.

If you add attachments, you have basically the same feature set as and can compete with Sharepoint, Confluence, Clearspace, etc.

At the same time, release it as open source. @Brian M. Hunt's reason #7 is probably the most important: "Open sourcing the project will destroy the motivation for an open source equivalent to arise in competition to your own project."

Leave out some key features (like AD integration, file attachments). Create a few plugins for essential features that aren't included with the open source product, and make them available for sale.

Let the community contribute features. Make a dead-simple plugin framework (following Wordpress's model) so the community has a low barrier to entry.

And, if it is open source, then (low- or no-budget) communities (such as students, user groups, etc.) that need a certain feature will be able to add it themselves.

  • 2
    Give me a dead-simple plugin framework and I'll give you Open-Source AD integration and attachments. Commented Oct 4, 2009 at 4:53

What about instead of open sourcing it, making it free to create a StackExchange site? You could keep all the advertising revenue. There's loads of great ideas out there, and I would hazard a guess that many of us would just like a SE site relating to our topic of interest, and aren't interested in trying to monetise it. For example, books.stackexchange.com or movies.stackexchange.com could easily become more successful than stackoverflow.

  • Not a bad idea .. so long as it was possible to run enough sites on little-enough hardware with enough Ad-clicks to pay for itself and those that run it. Commented Oct 4, 2009 at 4:51
  1. Currently, it wouldn't make any sense. Open source only make business sense when there is a community of users or businesses that find supporting a core software module/product useful for their business, but not part of their core business and thus to risky to devote resources to. By everyone contributing to the open code base, the risk is dispersed.

    • The classic example of this is the HTTP server. Every company needs one, but it rarely falls within a company's core business model.

    • In my opinion, SO as an application is distinct specialized enough that it is not a commodity, and therefore doesn't fall into the above category of software.

  2. Yes, if this is a core "engine" that ranks questions / answers / users, you could choose to open source that. For example, you could open source the "badges" component.

  3. Yes there are companies based on open source. You should evaluate how successful they have been and if their success matches up with your goals. Note that two of the companies you listed were acquired.

  4. Seems like you already have the answer to this question. Yes, I agree - you will be competing against open source clones, particularly in markets you may not have entered yet (Asia, Eastern Europe)

  5. See answer to #2 - if you want to provide an open source version of "Stack Engine" you could do so - but the only benefit would likely be goodwill of the community. As such, should not have the full features of the core site.

  • Linkage: The Commercial Open Source Business Model bit.ly/4Kv82
    – noahz
    Commented Jul 7, 2009 at 11:06
  • ZDNet op-ed on "The commoditization of software" - bit.ly/Zhvcw
    – noahz
    Commented Jul 7, 2009 at 11:21
  • Blog entry on commodification of software and relation to open source, by David Stutz: bit.ly/hc8RG
    – noahz
    Commented Jul 7, 2009 at 11:21

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