As with any business, you'd want to do due diligence. If I couldn't look at the code, I wouldn't buy it. Most web apps could be reproduced without ever looking

As with any business, you'd want to do due diligence. If I couldn't look at the code, I wouldn't buy it. Most web apps could be reproduced without ever looking at the code behind it, so allowing you to do so shouldn't be an issue. Buying a web app makes sense when: 1) you have a clear path to making more from it than you'd pay for it, in a short enough amount of time that it makes sense to buy the app rather than spend it elsewhere / develop it yourself. and you: a) have a relevant advantage that the current owner doesn't, like target market connections, a distribution network, or an app with complementary functionality. -or- b) can get an advantage with the app, that you need for something else.