title: How to manage multiple clients with slightly different business rules?
body: <p>We have written a software package for a particular niche industry.  This package has been pretty successful, to the extent that we have signed up several different clients in the industry, who use us as a hosted solution provider, and many others are knocking on our doors.  If we achieve the kind of success that we're aiming for, we will have literally hundreds of clients, each with their own web site hosted on our servers.</p>
  
  <p>Trouble is, each client comes in with their own little customizations and tweaks that they need for their own local circumstances and conditions, often (but not always) based on local state or even county legislation or bureaucracy.  So while probably 90-95% of the system is the same across all clients, we're going to have to build and support these little customizations.</p>
  
  <p>Moreover, the system is still very much a work in progress.  There are enhancements and bug fixes happening continually on the core system that need to be applied across all clients.</p>
  
  <p>We are writing code in .NET (ASP, C#), MS-SQL 2005 is our DB server, and we're using <a href="http://sourcegear.com" rel="noreferrer">SourceGear Vault</a> as our source control system.  I have worked with branching in Vault before, and it's great if you only need to keep 2 or 3 branches synchronized - but we're looking at maintaining hundreds of branches, which is just unthinkable.</p>
  
  <p>My question is: <strong>How do you recommend we manage all this?</strong></p>
  
  <p>I expect answers will be addressing things like object architecture, web server architecture, source control management, developer teams etc.  I have a few ideas of my own, but I have no real experience in managing something like this, and I'd really appreciate hearing from people who have done this sort of thing before.</p>
  
  <p>Thanks!</p>