I think what you are trying to say when you say "Why aren't there more open source web applications?" is something like "Why aren't there more web application s

I think what you are trying to say when you say "Why aren't there more open source web applications?" is something like "Why aren't there more web application sites that provide a service that are open source?" This I think is pretty simple. If I got your question right. If you are building a new site that does rss feeds aggregation with dynamic custom filters that track your web surfing to automatically rate content based on pages you spent time on, for example. Wow that was a mouthful. Err. Forget that. If you are building a better reddit.You have some new idea and that is your competitive edge and reason for doing the work. If you open source that you just gave away your reason for building your site. So there is a conscious decision to either build a site and try to monetize it, or build an open source platform and gain traction. The difference here is what you are trying to accomplish. If you are trying to differentiate a site with new technology or features you don't want to give away the secret sauce (source) to your incumbent competitors or your future competitors. While your busy focusing on and perfecting the technology. They can be busy focusing on getting to market. If google or ebay had open sourced their technology how hard would it be for Microsoft or Amazon to clone it and take it to the next level? If we use google as an example here. If microsoft could see exactly how page rank worked and the architecture that allows google to scale. Could they create their own version and possibly improve it. I think they could. If google open sourced in the beginning super live search would have happened before google got their ridiculous market share and google may not even exist today...